DICTIONARY OF
PHILOSOPHY AND PSYCHOLOGY

Me: see I and ME, and SELF.

Mean (1) and (2) Median [Lat. medius, middle, through Fr.]: Ger. (1) Durchschnitt, (2) Mitte; Fr. (1) moyenne, (2) not in use; Ital. (1) (quantità) media, (2) (valore) mediano. (1) When the term mean is used without qualification, it signifies the sum of a series of quantities divided by their number: the arithmetical mean, or average. Other kinds of mean are used, of which the geometrical mean is the most common. This is the square root of the product of two quantities.

The mean may be a representative quantity, as when it is found that the mean height of a certain class of men is 175 cm.; or it may be an approximation of a true value, as when it is found as the result of a number of measurements that the height of a man is 175.1 cm. The term average may with advantage be used for a representative value, and the term mean be confined to the precise mean.

(2) The median is the value midway in a series. In a large number of measurements following the distribution of the law of probabilities the median would coincide with the arithmetical mean. If, however, there are extreme values in one direction -- as in the reaction-time where long times may occur, but times departing to the same amount from the mean in the opposite direction cannot occur -- it may be an advantage to use the median. The median can also be used with qualitative differences, as the vividness of mental imagery or students' papers in an examination. Galton has used the median to advantage in such cases, the different degrees being divided into ten or four groups (deciles or quartiles). (J.M^cK.C.)

Galton defines the median: 'The accepted term to express the value that occupies the middlemost position. . . . The median M has three properties. The first, that the chance is an equal one of any previously unknown measure in the group exceeding or falling short of M. The second is, that the most probable value of any previously unknown measure in the group is M. Thus, if N be any one of the measures and u be the value of the unit in which the measure is recorded, such as an inch, &c., then the number of measures that fall between (N - 1/2u) and (N + 1/2u) is greatest when N = M. Mediocrity is always the commonest condition. . . . The third property is that whenever the curve of the scheme is symmetrically disposed on either side of M, except that one half of it is turned upwards and the other half downwards, then M is identical with the ordinary arithmetic mean or average' (Galton, Natural Inheritance, 41, which may be consulted also for mean and cognate conceptions). See MID-, and cf. ERRORS of OBSERVATION. (J.M.B.)

Mean (in ethics) [Gr. equiv. mesothV]: Ger. (rechte) Mitte; Fr. (juste) milieu; Ital. mezzo. That intermediate condition, removed alike from excess and from defect, which has been held to characterize virtuous or moral activity.

This conception occupies a central place in Aristotle's doctrine of virtue; but, in giving it that place, Aristotle only defined and rendered exact a conception which had become traditional. Greek views of life and art were from early times ruled by the conception of measure; the praise of moderation is found in Homer, and is a commonplace of the Seven Sages. Numerical definiteness was given to the same conception by Pythagoras, who seems to have identified the infinite or unmeasured with evil. In the Politicus, and still more prominently in the Philebus of Plato, the conception of measure is of fundamental importance, so that (as Sir A. Grant says) 'words like metriothV and snmmetria became naturally appropriated to express excellence in life and action.'

Through his conception of the mean Aristotle attempts to define the due moderation in which virtuous activity consists. But his conception is not merely quantitative. It is not the absolute or arithmetical mean (meson tou pragmatoV). This latter (which, as between two quantities, is equal to half their sum) has no place in morals. Virtuous action is a mean 'relative to us' or to the agent -- to meson to proV hmaV. It is not determined merely by abstract considerations, but is similar in character to the perfect harmony displayed in a work of art. Every morally virtuous habit or action is a mean between opposed extremes (which are vicious); but its distance from these extremes is not a matter of arithmetic, but is relative to a man's nature, and is determined rationally in accordance with the judgment of the man of moral insight (fronimoV). Further, Aristotle himself asserts that while the doctrine of the mean expresses the law of virtue, yet viewed in relation to the good, virtue is altogether opposed to vice, and is therefore, in this sense, an extreme. The doctrine of the mean -- le juste milieu, 'the golden mean' as it has been called -- may thus be said to express the aesthetic aspect of virtue or goodness. Aristotle's own statements might have guarded him from the misinterpretation to which Kant gave currency in saying that Aristotle made only a quantitative distinction between virtue and vice. (W.R.S.)

Mean Error: see ERRORS OF OBSERVATION, and PSYCHOPHYSICAL METHODS.

Mean Gradation (method of): see PSYCHOPHYSICAL METHODS.

Mean Variation: see ERRORS OF OBSERVATION. Cf. also PROBABILITY, and VARIATION (statistical treatment of).

Meaning [Gothic munan, Ger. meinen, to think]: Ger. Sinn, Meinung (OPINION, q.v.); Fr. sens; Ital. senso. A NOTION (q.v., sense 1) considered as having more remote bearings and relationships necessary to its adequacy, yet without abstracting from the image (see NOTION, sense 2) and without reference to the conative value of the notion (cf. INTENT). See TERMINOLOGY, English, 'Meaning,' for a further note on the foreign equivalents. (J.M.B., G.F.S.)

Meaning (in logic and grammar): see SIGNIFICATION, and UNIVERSE (in logic). Cf. SEMANTICS, and SIGNIFICS.

Meaning (in philosophy): see WORTH.

Means (to ends): Ger. Mittel; Fr. moyens; Ital. mezzi (al fine). Those end-states of voluntary determination which enter as elements into the voluntary determination of a larger end-state or terminus.

The phrase 'means to an end' denotes the psychological fact that while consciousness is pursuing the means, it is as elements in a larger whole which consciousness is also pursuing. Cf. END-STATE, and TERMINUS. (J.M.B., G.F.S.)

Measure of Precision: see ERRORS OF OBSERVATION.

Measurement [Lat. mensura, a measure]: Ger. Messung; Fr. mesure; Ital. misurazione. The determination of a magnitude in terms of a standard unit. Cf. UNITS OF MEASUREMENT, and NUMBER (concept of).

Exact science consists of measurements, and all sciences as they advance become increasingly quantitative. The fundamental UNITS (q.v.) of physical science are of space (size and direction), of time, and of mass (or energy). Counting is sometimes regarded as a kind of measurement, and a ratio is the basis of all measurement. The place of measurement in psychology is still an open question. Kant held that only the time of mental processes could be measured. Fechner attempted to measure their intensity, and more recently their extensity has been regarded as measurable. Could psychology measure these three magnitudes and count (i.e. collect statistics), it would have the same field for quantitative research as physical science. It has been claimed that only physical measurements are made in the psychological laboratory, but it may be replied that at all events mental processes are functions of the quantities measured.

These cases may be taken as illustrative of the following general principles: --

(1) That which is the subject of measurement is not a concrete object, but an attribute or condition associated with the object.

(2) This attribute or condition must depend upon some cause or agency susceptible of division into like parts which can, without ambiguity, be added to each other.

(3) The attribute or condition must be capable of definition without leaving any doubt as to the method by which it is to be measured. Otherwise, different modes of measurement may lead to different and inconsistent results.

Literature: WUNDT, Logik, IV. Absch., I. Cap. (2nd ed.); VENN, Empirical Logic; JEVONS, Princ. of Sci.; EVERETT, Units and Physical Constants. (J.M^cK.C.)

Measurement (principles of). The definitions of a concept qua object and qua magnitude or mathematical quantity should be sharply distinguished, and much confusion has arisen through assuming that the definition of a concept must include the definition of its measure as a quantity.

For example, the definition of a line is distinct from that of the word length, which expresses the magnitude of the line. Euclid defines a triangle in such a way as to imply that its measure is its area, when, in fact, the perimeter might equally be taken as the measure. A bar of iron may be measured by its mass, volume or its length. Which measure we shall take is logically a matter of arbitrary definition, and, practically, a question of convenience. The measurements of temperatures by two thermometers of different materials cannot be brought into agreement through the entire range of observable temperatures. It is therefore desirable, in using any concept as a quantity, always to indicate what the nature of the quantity is, as lines of equal length, triangles of equal area, instead of equal lines and triangles.

In order that a concept may be measured as a mathematical quantity without ambiguity, it is essential that the special attribute by which we measure it should be conceivable as made up of discrete parts, admitting of unambiguous comparison inter se, with respect to their equality or difference of magnitude. The simplest case is that of a straight line, whose length we conceive to be made up of distinct metres, centimetres, millimetres, or other units taken at pleasure, each of which can be determined by bringing it into coincidence with a movable measure of the designated length. Quantities of heat may be measured on the same system. But such is not the case with increments of temperature. Were it a universal rule that equal quantities of heat produce proportionate increments of temperature in all bodies, there would be no difficulty in measuring temperature by quantities of heat. But such is not the case, so that the absolute equality of increments of temperature has to be defined by thermodynamic considerations.

A more complex, but very instructive case, showing how the relation of equality between magnitudes is a matter of definition, is afforded by light, or, as the writer prefers to call it, radiance in general, whether visible as light or not. The intensity of a homogeneous ray emanating from a point and falling on an eye is capable of unambiguous definition, because equal quantities of radiance may be added without limit. Still, the measure will be definite only for a given eye at a given distance with a fixed opening of the pupil. If the distance increases, the apparent intensity of the radiance diminishes; it will be different with different eyes; it will vary with the diameter of the pupil of the same eye.

Radiance may be measured by two effects: effect on the eye, and quantity of energy conveyed by the ray. These will give accordant results in the case of any one homogeneous ray. But if rays of different wave length be compared, equality of optical effect will not correspond to equal quantities of energy. (S.N.)

Measurement Formula (psychophysical): see FECHNER'S LAW.

Mechanical [Gr. mhcanh, a machine]: Ger. mechanisch; Fr. mécanique; Ital. meccanico. A term used, in antithesis to organic and teleological, to describe any theory which proposes to eliminate final causes from philosophy, and to explain all phenomena as the necessary outcome of the general laws of matter in motion; and also applied to the world as thus explained. That which is strictly mechanical is called a machine or a mechanism. (A.S.P.P.- J.M.B.)

The term is used by Aristotle, and maintained itself during the middle ages, but the philosophical opposition between a mechanical and an organic or teleological view of the universe associates itself with the term only in modern times. Descartes' saying, 'Give me matter, and I will construct the world' -- including in the world of phenomena of life, everything, indeed, except the res cogitans in man -- formulated the protest of modern science against the 'forms' and inner powers of scholasticism. Boyle, one of the most enthusiastic apostles of 'the new philosophy,' expressly uses the term mechanical to describe the new view (cf. his treatise on The Excellence and Grounds of the Mechanical Philosophy). It is freely used in the same reference by Berkeley in Siris, who maintains, however, that 'the mechanical philosopher inquires properly concerning the rules and methods of operation alone, and not concerning the cause; forasmuch as nothing mechanical is, or really can be, a cause' (Siris, § 249; cf. §§ 236, 247). Boyle himself did not deny that the mechanical philosophy required to be supplemented by 'an inquiry into the final causes of natural things.' But Spinoza, in his passionate polemic against the idea of end, uses the term mechanical to denote the true and complete explanation as opposed to explanation by means of supernatural or miraculous agency. It is significant that the example he takes is the frame of the human body, which has furnished so many 'arguments from design.' The common run of thinkers, he says, 'ubi corporis humani fabricam vident, stupescunt, et ex eo, quod, trantae artis causas ignorant, concludunt eandem non mechanica sed divina vel supernaturali arte fabricari, talique modo constitui ut una pars alteram non laedat' (Ethica, i, Appendix). Leibnitz's philosophy is a systematic demand for mechanical causation, and at the same time to do justice to the philosophical demand for teleological explanation which Aristotle and the older philosophy had striven to satisfy. Causae efficientes pendent a finalibus may be taken as the motto of his thinking. In a not dissimilar spirit, Kant distinguishes between the mechanical causality which governs nature or the world of phenomena, and the free ethical causality of 'the realm of ends' of which man's reason and will constitute him a citizen; while Lotze declares, in the spirit of Leibnitz, that the aim of his philosophizing is 'to show how absolutely universal is the range of mechanism, and at the same time how completely subordinate the significance of the function which it has to fulfil in the structure of the world' (Introd. to the Microcosmus). Cf. the discussion of the supposed antithesis between natural selection, as mechanical, and teleology given under HEREDITY, and see NATURALISM (1).

In biology: mechanism is opposed to vitalism, and in more recent controversy to neovitalism, as in the term DEVELOPMENTAL MECHANICS (q.v.), in which morphological changes are treated from the strict point of view of cause and effect.

Literature: EUCKEN, Gesch. u. Krit. d. Grundbegriffe d. Gegenwart; JANET, Final Causes; TRENDELENBURG, Hist. Beitr., ii, Ueber den letzten Unterschied der philosophischen Systeme; WARD, Naturalism and Agnosticism. (A.S.P.P.)

Mechanical Equivalent (of heat): Ger. mechanisches Aequivalent; Fr. équivalent mécanique; Ital. equivalente meccanico. The amount of mechanical work that must be expended in order to produce a unit of heat; generally the amount of energy which, by its disappearance, will create a unit of heat.

The equivalent is commonly expressed in terms of WORK (q.v.), the most convenient method of determination. See also ENERGY. (S.N.)

Mechanics [Gr. mhcanikoV, pertaining to mechanics]: Ger. Mechanik; Fr. mécanique; Ital. meccanica. The science which treats of the effects of force in causing motion or equilibrium.

Theoretical mechanics: the science of mechanics treated in a general way, solely with regard to the principles involved.

Applied mechanics: the application of the laws of mechanics to practical purposes, such as the strength of materials and the working of machinery. See also MECHANICAL. (S.N.)

Mechanics of Ideas: see MECHANISM (of mind), and HERBARTIANISM.

Mechanism: see MECHANICAL.

Mechanism (of mind or ideas): Ger. Mechanismus; Fr. mécanisme; Ital. meccanismo. That explanation of mental process which traces it to the uniform behaviour of certain relatively simple and homogeneous elements, after analogy with particles of matter in motion.

The term was given currency by Herbart, who essayed to work out a 'Mechanik der Vorstellungen,' in which the rise and fall (Steigen und Sinken) of ideas were accounted for in terms of physical and mechanical principles. The term is not good, since it lends itself to interpretation in terms of physical analogy. (J.M.B.- G.F.S.)

Mediacy: see IMMEDIATE AND MEDIATE.

Mediacy or Mediation (Vermittelung): see HEGEL'S TERMINOLOGY, IV, V.

Median: see MEAN, and MID-.

Mediate: see IMMEDIACY AND MEDIACY, IMMEDIATE AND MEDIATE, (mediate) INFERENCE (2), MEDIATE (in theology), and MEDIATION.

Mediate (in theology) [Lat. mediatus]: Ger. vermittelnd; Fr. médiat; Ital. mediato. In religious thought, a term which characterizes the indirect agency of God in relation to man and the world. See MEDIATION.

According to the prologue of St. John's Gospel the creation of the world is mediated by the Divine Logos, while according to the Book of Genesis the development and organization of the world is mediated by the Holy Spirit. In the Christian scheme the salvation of man is mediated by the Divine Logos in the incarnation, the atonement, and the process of redemption. The idea of mediate agency is found in pre-Christian philosophy, especially in the system of Philo of Alexandria, who conceives God as purely transcendent and introducing subordinate beings or Logo to mediate his agency in the world. (A.T.O.)

Mediation [Lat. mediatio]: Ger. Vermittlung; Fr. médiation; Ital. mediazione. (1) The mode by which a transcendent Deity is enabled to produce effects in the world without being himself the immediate agent of these effects.

(2) In Christian theology: that agency of Christ as revealer and atoner, by and through which man is redeemed from his ignorance and sin, and becomes reconciled with God.

The germ of the notion of mediation is contained in the Hebrew conception of Jehovah, and also in the Greek Logos. It became explicit in the Alexandrian thought of Philo, whose highest Logos was represented as performing the office of mediator between God and the world, thus making it possible for God, who is conceived in a purely transcendent fashion, to produce effects in the world without being contaminated by its evils. Mediation is the central idea in the Christian doctrines of atonement and redemption.

Literature: see references under ATONEMENT, and LOGOS. ZELLER, Philos. d. Griechen, Pt. III (1869); KIFERSTEIN, Philos. Lehre v. d. Göttlichen; HEINZE, Lehre v. Logos (1872). (A.T.O.)

Medical Psychology: Ger. medizinische Psychologie; Fr. psychologie médicale; Ital. psicologia medica. The consideration, mainly from a medical point of view, of abnormal and pathological mental states, and their symptoms.

With this meaning the term 'psychological medicine' (see Bucknill and Tuke, Manual of Psychol. Med., 1858, and later Tuke, Dict. of Psychol. Med., 1892) is also used. British and French associations for the study of the insane bear the name 'Medico-psychological Association.' Lotze, in his Medicinische Psychologie (1852), included what was later termed physiological psychology, or mental physiology (Carpenter and Maudsley). The term is closely related to psychiatry, psychopathology, abnormal psychology, and PATHOLOGY (mental) (q.v.), especially the last-named. (J.J.)

Meditation [Lat. meditatio]: Ger. Nachdenken; Fr. méditation; Ital. meditazione. A somewhat loose synonym for REFLECTION (q.v.). Not a technical term. (J.M.B.)

Medium [Lat. medium, middle = Gr. mesoV]: Ger. Medium; Fr. médium; Ital. medium, medio. A term applied, in connection with the phenomena of ANIMAL MAGNETISM (q.v.), HYPNOTISM (q.v.), and SPIRITUALISM (q.v.), to a person whose speech and action are supposed to be controlled by a foreign personality or by a disembodied spirit, and who speaks from knowledge gained in some supernatural manner; also called a 'sensitive.'

Some spiritualistic and other mediums claim the power of acting upon matter in violation of ordinary physical laws; others claim to be the means of communication between the departed and the living. As such communications are frequently given while the medium is in an abnormal, semi-conscious condition (usually termed TRANCE, q.v.), the explanation of the phenomena of mediumship may possibly be sought in a psychological analysis of such quasi-abnormal conditions. That many of the claims and exhibitions of alleged mediums are little more than vain pretence and more or less clever deceit has been abundantly proved; but in many other cases the phenomena must be considered genuine.

A case which may be cited as a typical form of the phenomena as exhibited in recent years is that of Mrs. Piper (cf. Proc. Soc. Psych. Res., xii-xv). For the various manifestations of mediums in SPIRITUALISM and in TRANCE conditions see those terms. Anthropologically, the medium is variously represented in the Shaman or medicine man, in oracles, and in superstitions, customs, and beliefs relating to the influence of the dead upon the living. See VOODOO, FETICH, and MAGIC. Cf. general treatment in Lehmann, Aberglaube und Zauberei, and the citations under SPIRITUALISM. (J.J.)

Medium (in philosophy): see TERTIUM QUID, MILIEU, and ENVIRONMENT.

Megalomania [Gr. megaV, great, + mania, madness]: Ger. Megalomanie; Fr. mégalomanie; Ital. megalomania. A special form of delusion occurring in certain forms of insanity (cf. in particular, MANIA, and general PARALYSIS), in which the patient feels himself elated, his energies overflowing, his mind filled with a wealth of brilliant thoughts, his strength gigantic, his possessions vast, his achievements remarkable, his powers supreme, &c.

To keep pace with these exalted notions he invents the most brilliant accounts of his endowments and possessions. He is a genius among mankind, can speak a score of languages, has a wonderful voice, the skill of a Rembrandt; he has estates in all parts of the world, has thousands of servants, is about to establish vast mercantile operations; he has distinguished himself in battle, is a hero among the fair sex, is about to assume command of armies; or he has great schemes for making everybody wealthy, for reforming mankind, and so on indefinitely. The notions often assume the most extravagant forms, particularly as the brain disease advances. The megalomaniac poses as an emperor, as the son of Venus, as the ruler of the earth, as God himself. The patient is absorbed in these exalted reflections, which he is ever ready to extend and expand, and does not realize the contradiction between his actual surroundings and the ideal world in which he lives. Synonyms of megalomania are 'expansiveness' and 'exaltation.' Cf. DELUSION. (J.J.)

Literature: treatises on mental PATHOLOGY (q.v.), especially those of DAGONET, SCHÜLE, CLOUSTON, KRAFFT-EBING, KRAEPELIN, and BALLET-MORSELLI; also EMMINGHAUS, Allg. Psychopathol.; FRIEDMAN, Ueber den Wahn (1894). (E.M.)

Megarians: see SCHOOLS OF GREECE, II.

Melancholia [Gr. melaV, black, + colh, bile]: Ger. Melancholie; Fr. mélancolie; Ital. malinconia. In its current use melancholia applies to all abnormal mental conditions dominated by depression, while formerly it was a synonym of partial insanity or MONOMANIA (q.v.). According to Pritchard, the Greek melagcolan means simply to be mad, without any reference to lowness of spirits. The term was opposed to mania, and became more and more connected with gloom in the sense in which it is used exclusively to-day. Esquirol felt obliged to call the depressive insanities proper, lypémanie, in order to escape confusion. Rush uses the term Tristomania.

The varieties commonly classified are simple melancholia, stuporous, delusional, homicidal, suicidal, puerperal, acute, chronic melancholia attonita, &c. It is obvious that many dissimilar conditions are thus brought under one heading, simply because they are dominated by depression. A careful analysis leads to the recognition of more essential characteristics; but the nosological interpretation of the various types is still a topic of some controversy.

The following are the most common symptom-complexes: (1) Constitutional depression: a pessimistic temperament that is inclined to see the dark side of everything, and is led to gloominess and despondency upon slight provocation. Such moods or periods often present a temporary character in the form of more or less periodic exacerbations, which, however, in distinction from the next group, rather readily pass off with an improvement in the circumstances of the patient. Such attacks are occasionally accompanied by marked feelings of anxiety.

(2) Simple melancholia proper: an excessive or altogether unjustified depression, often accompanied by defective sleep, precordial pain or uneasiness; a susceptibility for the unpleasant and wearing aspect of things only, and a feeling of self-depreciation, of sinfulness, without insight into the unwarranted morbid nature of the condition. The patient feels himself too bad to live or to be treated kindly. There is usually a feeling of inability and indecision, and especially in the form which is merely a phase of manic-depressive insanity (see MANIA), a difficulty in thinking clearly, and a retardation or inhibition of spontaneous activity.

This may be followed by delusional elaboration; the patient comes to believe that everything, the whole world, will come to a bad end, that it is all the patient's fault; and an occasional hallucination may appear to corroborate and elaborate such feelings and thoughts. This condition is frequently accompanied by a strong affect of fear and anxiety for self and family, or suicidal impulses, or great restlessness, or again self-absorption, or retardation of all activity, leading to a form of stupor.

(3) Other forms are characterized by prolonged 'neurasthenic' malaise and a feeling of depression (frequently over moral matters), and by a great tendency to refer the feelings to influence of others, to poison, to hypnotism, to electricity, to nocturnal rape; or there are hypochondrical complaints, frequently of an absurd character. Hallucinations are common. The whole picture is apt to have a certain resemblance to the paranoic types in later periods of life (after 35), while in earlier periods it undoubtedly belongs usually to the processes of deterioration (dementia praecox), and often presents distinct features of katatonia.

(4) Depressive delirium, together with great anxiety, vivid hallucinations, fear, desire to escape from danger, even by suicide, sometimes with remarkably good appreciation of the immediate circumstances and environment. It is apt to occur after acute diseases, in pregnancy, &c., and is at times difficult to distinguish from alcoholic delirium.

(5) As a special episode in the types (2) and (4) may be mentioned the délire de négation (délire in the broad sense of delusional state); the patient believes that he is nobody, that the whole world is imaginary, gone, burned, 'everybody dead and nobody left to tell the tale,' &c. A similar exaggeration of depressive delirium occasionally occurs in senile dementia and in general paralysis.

(6) 'Katatonic melancholia,' for which see KATATONIA. It is perhaps closely related to type (3), but usually of acute onset, with hallucinations of commands to be good, to perform simple actions that have a mystical and symbolic meaning (spitting at a shoe, taking attitudes of prayer and poses, &c.); with catalepsy, mutism, refusal of food, stupor, often with perfect knowledge of what is going on and perfect remembrance of incidents. The occasional excitements show stereotypy of expression, and lead frequently to repetition of sentences (e.g. 'give me a dose of poison to put me out of the way quick,' repeated continually for months), or of senseless sounds or confused silly talk with reiterations (verbigeration). Rather often sudden recovery occurs, if the first attack does not lead to dementia.

The forms (1) and (2) are usually recoverable conditions of greatly varying duration, frequently belonging to the constitutional, recurring, and circular psychoses, the simple depressions being especially prone to occur in several successive generations of a family. In the circular cases, the predominance of an inhibition or retardation of movements and of thought is very striking, while the anxious and agitated forms of type (2) are especially characteristic for the climacteric period, and pass without a distinct line into the type of presenile depression with absurd hypochondriacal delusions, shallow affects, and usually poor prognosis. Many cases of type (4), as well as of (3), are processes of deterioration (dementia praecox), or, in a later period of life, of paranoic conditions.

The individual differences in a large series of cases of melancholia are so great that it would be a grave injustice to the facts to try to describe them as one condition in one connected composite picture.

Clinical experience and experimental psychology show that there are undoubtedly several distinct disease processes which account for the differences of the above types. But definite statements as to their nature and concerning the pathological anatomy seem as yet premature.

Literature: KRAEPELIN, Psychiatrie, ii (1899), and Die klinische Stellung der Melancholie, Monatssch. f. Psychiat. u. Neurol., iv. 325 (1899); ROUBINOWITSCH and TOULOUSE, La Mélancolie (1897); TH. ZIEHEN, Die Erkennung und Behandlung der Melancholie in der Praxis, Alt's Abhandl., i (Halle, 1896); also Amer. J. of Insan., liv. 543; VALLON and MARIE, Le délire mélancolique. Arch. de Neurol. (June, 1898); TOULOUSE and VASCHIDE, Le Temps de Réaction dans la Mélancolie, Rev. Neurol., v. No. 22; E. RÜCKLE, 1st die Melancholie ausschliesslich eine Psychose des Rückbildungsalters? Diss. Erlangen (1898); G. M. ROBERTSON, Melancholia from the Psychological and Evolutionary Point of View, J. of Ment. Sci. (1890) J. K. MITCHELL, An Analysis of Three Thousand Cases of Melancholia, Trans. Assoc. Amer. Physiol. Philad., xii. 480, and J. of Nerv. and Ment. Dis., xxiv. 738 (1897); E. N. BRUSH, An Analysis of One Hundred Cases of Acute Melancholia, Brit. Med. J. (Sept. 25, 1897), and Amer. J. of Insan., 1iv. 241; J. SÉGLAS, Le Délire des Négations (Paris, 1896); general treatises on psychological medicine by MOREL, GRIESINGER, KRAFFT-EBING, SCHÜLE, and BALLET-MORSELLI; and a discussion in Neurol. Centralbl. (1899), 904. (A.M.- E.M.)

Melanchthon (or Melancthon), Philip. (1497-1560.) Enjoyed unusual educational advantages under the supervision of his grandfather and of Reuchlin, who translated his name Schwarzerd ('Black earth') into the Greek 'Melanchthon.' Entered the University at Heidelberg, 1510; removed to Tübingen 1512, where in 1514 he began lecturing on the classics. In 1518, declining calls to both Leipzig and Ingolstadt, he went to Wittenberg, where he was associated with Luther, who, together with the students, induced him to turn his attention to theology. He wrote and repeatedly revised the Augsburg Confession.

Meliorism [Lat. melior, better]: Ger. Meliorismus, Theorie der Weltverbesserung; Fr. méliorisme (not in use); Ital. migliorismo. A belief in the possibility of the improvement of the world by human effort, generally implying the further belief that such progressive improvement is a fact and even a law of evolution. (A.S.P.P.- H.S.)

The term was invented by George Eliot, in connection with the question of optimism and pessimism, to express a view which she put forward as a via media between these two extremes (see an article on George Eliot by Edith Simcox in the Nineteenth Century for May, 1881). Used by her in conversation, it was adopted by Sully in his Pessimism (1877), and has since become current. Sully defines it as 'the faith which affirms not merely our power of lessening evil -- this nobody questions -- but also our ability to increase the amount of positive good. . . . By recognizing the possibility of happiness and the ability of each individual consciously to do something to increase the sum total of human welfare present and future, meliorism gives us a practical creed sufficient to inspire ardent and prolonged endeavour' (Pessimism, 399). The belief connects itself with the modern theory of evolution, which it interprets in a beneficent and quasi-religious light. 'Faith in a gradual abatement of evil by the method of progressive evolution is now a favourite scientific faith: this faith may be regarded as the form which an unconsciously religious conception of the universe is assuming in professedly agnostic minds' (Fraser, Theism, 2nd ed., 282). Cf. OPTIMISM AND PESSIMISM (also for Literature). (A.S.P.P.)

The English meliorate and melioration (the usual form being ameliorate, from ad + melioratus) might well be used (Ger. verbessern, Verbesserung; Fr. améliorer, -ation; Ital. migliorare, miglioramento) in connection with meliorism. (J.M.B.)

Melissus. Lived about 450 B.C. Born in Samos. He is called a disciple of Parmenides. His work is prose (peri fuswV or peri ontoV), of which fragments remain, is a refutation of the Ionian Physicists. He was also victorious as a naval commander in battle with the Athenians.

Melody: see MUSIC.

Memory [Lat. memoria]: Ger. Gedächtniss, Erinnerung (princ. in compounds); Fr. mémoire; Ital. memoria. Ideational process, so far as it takes the form of the reproduction and recognition of prior experiences in their original time order. Memory thus includes the three relatively distinguishable functions of REPRODUCTION, RECOGNITION, and LOCALIZATION (in time). Cf. those terms.

Plato calls memory swthria aisqhsewV (Philebus, 34 A). This failed to distinguish between memory proper and retentiveness in general. Aristotle, however, distinguished between fantasia and mnhmovenma. Hobbes defines both memory and imagination, which with him includes all mental imagery as 'decaying sense.' The word memory is used to indicate that the mental image presupposes a primary experience, which it revives. The word imagination is used to indicate that the revival is relatively faint, or, as Hobbes would say, 'decayed.' Locke says that memory is 'the power the mind has to revive perceptions which it has once had, with the additional perception annexed to them -- that it has had them before' (Essay, Bk. II. chap. x. § 2). Hume raises the question of the difference between memory and imagination. According to him the distinction is one of degrees of vivacity. The vivacity or liveliness of an experience coincides with Hume with power to compel belief in the object of the experience. Vivacity -- and therefore belief-compelling power -- belongs in the highest degree to actual sensations, or, as he calls them, impressions. 'We find by experience that, when any impression has been present with the mind, it again makes its appearance there as an idea, and this it may do after two different ways, either when in its new appearance it retains a considerable degree of its first vivacity and is somewhat intermediate between an impression and an idea, or when it entirely loses that vivacity and is a perfect idea. The faculty by which we repeat our impressions in the first manner is called the memory, and the other the imagination' (Treatise on Human Nature, i. 193). Reid has a very good chapter on 'Theories concerning Memory' (On the Intellectual Powers, Essay III, chap. vii), in which he criticizes the definitions of Locke and Hume. He remarks that Locke is inaccurate in saying that the perception itself as a mental occurrence is revived. 'An ability to revive our ideas or perceptions, after they have ceased to be, can signify no more than an ability to create new ideas or perceptions similar to those we have had before' (Essay III, chap. vii. 355, Hamilton's edition). The true way of putting the case, according to Reid, is to say that the memory-idea is a thought of the same object as that which had been originally perceived. The same criticism applies to Hume. Reid also urges against Hume that he defines in a circle. 'For can we find by experience that an impression, after its first appearance to the mind, makes a second and third, with different degrees of strength and vivacity, if we have not so distinct a remembrance of its first appearance as enables us to know it on its second and third, notwithstanding that, in the interval, it has undergone a very considerable change?' (ibid. 354). 'It has been held by some psychologists that memory proper includes the representation of one's past self as agent or patient in the event or situation recalled. And this is true as regards all but the earliest human experience, at any rate; still, whereas it is easy to see that memory is essential to any development of self-consciousness, the converse is not at all clear, and would involve us in a needless circle' (Ward, art. Psychology, Encyc. Brit., 9th ed., xx. 63). Cf. the topics immediately following; also ORGANIC MEMORY. (G.F.S.- J.M.B.)

Recently the question of 'affective memory' has arisen for discussion. See REVIVAL.

Literature: the works named; the textbooks of psychology (citations are made in those of DEWEY, BALDWIN, LADD, JODL, and JAMES); the Psychological Index, 1 ff.; the following topics; BIBLIOG. G, 2, u; EISLER, Wörterb. d. philos. Begriffe, 'Gedächtniss.' On affective memory, see URBAN, Psychol. Rev., viii, May, July, 1891, 262. (J.M.B.)

Memory (defects of). Abnormalities of memory fall readily into the two classes of excess and defect. An equally fundamental distinction is that between affections of general retentiveness and affections of special acquisition groups, i.e. classes of memories.

The nature of the case, whether mere absence of memory, distortion of memory, illusion of memory, or, again, whether temporary or permanent, periodic or progressive, is also of great importance. The most general synonym for defect of memory is AMNESIA (q.v.), which, however, when used with precision, applies only to degrees of failure of retentiveness. Paramnesia indicates a defect of distortion or illusory memory, a false recollection; hypermnesia refers to conditions of unusual exaltation of memory.

Any adequate account of defects of memory must be based upon, and developed in conformity with, an analysis of the normal functions which the term comprises. Normal memory is an expression of the functional activity of the nerve centres, whereby, on the basis of vestiges or residua established as concomitants of sense impressions, of actions, of emotions, or in brief of experience, the same or similar presentations are recognized when they recur, enter freely into combination with other remembered presentations, and may be more or less successfully summoned into consciousness by voluntary effort. Residua of some sort are thus an indispensable requisite of all acquisition, whether carried on subconsciously and automatically or with conscious intent. In the larger sense we remember how to walk as well as how to talk; we remember the use of a knife or the sound of a printed letter; we remember the odour of tuberose or the exhilaration of a toboggan slide; we remember, too, what we liked in our childhood, or the scenes of former travels; we remember that boeuf is the equivalent of ox, or that 622 is the date of the Mohammedan Hegira. It is obvious that memory -- an with its defects of memory -- comprises a very heterogeneous assemblage of processes, which reflect the variety of psychological functions involving the memory factor.

A defect of memory is an expression of the incapacity of a group (or of certain groups) of centres to exercise their normal functions, or of a tendency which they show to function in an abnormal manner. Thus considered, defects of memory may be (1) general, involving (a) a defective capacity of a nervous centre (or centres) to establish residua or dispositions of memory; in this condition an object not in the range of vision is forgotten, an action just performed is as though it had not been done at all, and may be repeated again and again without becoming familiar; (b) or it may be that this power is exalted so that impressions reappear in memory with unusual completeness and vividness. Along with normal power to revive in memory current acquisitions, the defect may be (2) special: a loss of certain experiences from the memory accumulations of the past; and this again either temporarily or permanently. After an accident, the experiences of minutes or hours or days preceding the moment of the accident are often forgotten; the recovery from fever leaves a blank in the patient's memory continuum; in cases of periodic changes of personality and of hypnotic states, the subject in one period is ignorant of his experiences in the other, and it may be to such an extent that manual facility and other automatic accomplishments as well as intellectual acquisitions are involved. (3) It may be that only certain groups of images fall away: one patient loses the power to recognize printed letters or to recall the manner of making the sounds which they indicate, while retaining the power to speak and to understand conversation (see SPEECH AND ITS DEFECTS); another loses the memory of a foreign language while retaining his vernacular; another loses the memory for substantives or proper names, and so on. (4) The abnormality may consist in a false localization in time, of false concomitants or order of the same; of imaginary additions to real events; of the entire illusory recollection of what has not been experienced, the apparent familiarity of what is really novel, and the like.

Briefly, the memory functions may be altered in regard to their 'storing' or retentive functions; in regard to their reproductive functions (the recorded impressions in part or in whole, for shorter or longer periods, are not recalled or not recognized); or, finally, the reproductive or recognitive function may be inadequately or in some one of many ways perversely performed.

No adequate account of memory defects along the line of this classification (which may be characterized as an internal classification depending upon variations from normal functional activities) has as yet been made, but it is clear that the familiar cases of such defect are readily interpretable on this basis.

(1 a) may be termed acquisitional amnesia, and occurs both temporarily and permanently in imbeciles, in dementia, and as the result of serious shock or injury. As elsewhere, certain groups of centres may be more closely involved than others. (1 b) represents hypermnesia; it may be exhibited as unusual scope of memory (arithmetical prodigies, chess-playing virtuosi like Zuckertort or Pillsbury playing twenty games at once and blindfolded, considered as abnormal); or unusual celerity, accuracy, or vividness; or may combine these qualities in various proportions. As before, such hypermnesias may be generally distributed, but are more apt to affect special groups of centres. Group (2) constitutes the ordinary special amnesias, temporary, or permanent, or periodic, and may affect subconscious and automatic, or (more usually) voluntary acquisitions alone. They are related to defective nutritional or generally degenerative conditions of cerebral centres, and are apt to involve more or less serious impairments of consciousness. See PERSONALITY (defects of), and SUBCONSCIOUS. (3) represents the various partial amnesias, while (4) represents the equally varied paramnesias and illusions of memory.

Regarding illusions of memory, many fall entirely within the bounds of the normal. Forgetting is as normal as remembering, and misremembering is a form of forgetting. In experiments upon memory as well as in studies of mal-observation, errors of memory are usually classified as those of omission, of substitution, of transposition, and of addition. Material may be omitted, may be falsely localized, may be confused with other data, and extraneous matter may be introduced. The normal laws of association and specialization of memories are competent to account for such errors in general outline, though not in detail. In addition, there are more obscure illusions, which have been classified (Burnham) as (a) simple paramnesia or the confusion of the results of imagination with true memory images; in this way habitual liars come to believe their own inventions, and the systematic delusions and accusations of the insane may find a starting-point in a similar pseudo reminiscence (Kraepelin); (b) identifying paramnesia, also termed double memory, which is the above-mentioned false familiarity, the 'has-been-experienced-before' consciousness; this too occurs in normal persons, and may occur in insanity with unusual fullness of detail, the patient feeling that the thing about to be done has been done before, and that he can anticipate what is to occur next; (c) suggestive or associating paramnesia, in which actually occurring impressions arouse false reminiscences; in this way suggestions that one has experienced things which have not been experienced are accepted, and false testimony is produced frequently by children (MOTET, cited below); it may also be that certain types of presentiments are really cases of similar pseudo-reminiscences.

The more usual method of classification approaches the subject externally, on the basis of the character of the symptoms; and such a classification, while not antagonistic to the one just outlined, results in a different exposition. It is best represented by Ribot, who proceeds as follows: --

(1) General amnesia, which is (a) temporary, or (b) periodic, or (c) progressive, or (d) permanent, and is either congenital, as in idiocy, or acquired, as in severe dementia; (2) partial amnesia; (3) hypermnesia.

With regard to the occurrence of memory defects, it may be noted, in addition to the illustrations above cited, that temporary defect may be produced by fatigue, by anxiety, &c.; it appears as a marked characteristic of epileptic seizures (see EPILEPSY), as an effect of shock or injury to the brain, and as the result of the action of drugs (see PSYCHIC EFFECT OF DRUGS). More permanent amnesias occur in the general debility of illness or old age, and in profound affections of the brain, as in mania, melancholia, dementia. In hysteria occur at times peculiar periodic dislocations of the memory basis, which tend to divide the experiences of the patient into relatively independent and unrelated memory systems (for details see references under HYSTERIA, and defects of PERSONALITY). Typical cases of progressive amnesia (and the same is true of partial amnesia) are recorded in connection with aphasic disorders and in general paralysis. Hypermnesia occurs as an individual endowment, and in response to the stimulation of drugs, of fever, of hypnotic suggestion, and states of normal or abnormal mental excitement. The occurrence of some one form of unusual special memory in combination with mediocre general ability, or even with imbecility, has been noted.

Literature: RIBOT, Diseases of Memory (Eng. trans., 1882); GUILLON, Les Maladies de la Mémoire (1897), a monograph on hypermnesia, with bibliog.; PATRIZI, Memoria e Oblio (1890), with bibliog.; SULLY, Illusions, chap. x; BURNHAM, Amer. J. of Psychol., ii. 39, 225, 431, 561 (with bibliog., 431 on abnormal memory); KRAEPELIN, Arch. f. Psychiatrie, xvii. Heft 3, xviii. Hefte 1 and 2; ROYCE, Mind, xiii. 244; HODGSON, Proc. Soc. Psych. Res., iv. 381; DAVEY, ibid., 405; MOTET, Les faux Témoignages des Enfants (1887); OSBORN, Illusions of Memory, North Amer. Rev. (1884), 476; PARDO, I Disturbi della Memoria (1899); SOLLIER, Troubles de la Mémoire (1892). General works on MEMORY (q.v.) often contain data regarding abnormal memory. See also under SPEECH AND ITS DEFECTS. (J.J.)

Memory (experiments on). Four experimental methods of investigating memory are sometimes distinguished: those of 'reproduction,' 'identification' ('recognition'), 'selection' (comparison'), and 'description.' All investigations so far published, however, may be classified under the first two heads. Widely defined, description belongs to reproduction, and comparison may be considered a function of recognition. (E.B.T.- J.M.B.)

It is clear that various bases of classification of problems and literature might be taken. Thus one might arrange them under the sense-organs to which the stimuli employed appeal. A good classification is that in terms of attribute of stimulus, under five heads (cited with authorities): --

(1) Time (Paneth, &c.); (2) Space (Baldwin, &c.); (3) Intensity (Weber, &c.); (4) Quality (Wolfe, &c.); (5) Composition (Ebbinghaus, &c.). (E.B.T.)

The methods have recently been classified and criticized. Kennedy (Psychol. Rev., v. 477) reviews the subject and finds much confusion from the failure to discriminate the methods with exactness. In his opinion the three methods distinguished by Baldwin (under the terms reproduction, identification, and selection), and suggested and used also by Binet (under the terms reproduction, recognition, and comparison), are psychologically distinct from one another. These writers hold that the circumstances of 'recognition' -- as between mere identification of a recurrent stimulus and its 'selection,' with 'comparison,' from others -- are all-important, and justify the careful separation of these methods (cf. the general statement by the present writer, Story of the Mind, 138 ff.). The method of 'description' is hardly a memory method, since it really gives exercise to association and apperception (in its wider sense), as Ebbinghaus clearly shows in his attempt to give it exactness (Sitzber. d. 3^ten Int. Cong. d. Psychol., München, 1896). (J.M.B.)

The psychological basis of Kennedy's classification is criticized by Bentley (Amer. J. of Psychol., xi. 1), who distinguishes between reproduction and recognition, making the other methods mentioned sub-types of one of these; he adds a third method, 'recall and comparison,' which takes account of the memory image. Reproduction and recognition possess quantitative value chiefly; recall and comparison, qualitative as well. (E.B.T.)

Literature: more general titles are BURNHAM, Amer. J. of Psychol., ii. 39, 225, 431, 568 (with bibliog.); JAMES, Princ. of Psychol., 'Memory'; KENNEDY, Psychol. Rev., v. 477 (bibliog. to July, 1898); BENTLEY, Amer. J. of Psychol., xi. 1 (bibliog. to 1899); BALDWIN, as cited above. Researches classed roughly by methods (the stimulus is also given in some instances) are: --

(1) Reproduction and Description: EBBINGHAUS, Ueber d. Gedächtniss (1885); MÜLLER and SCHUMANN, Zeitsch. f. Psychol., vi, Syllables; PANETH, Centralbl. f. Physiol., iv, Time Intervals; MÜNSTERBERG, Beitr. z. exper. Psychol., iv, 'Muscular' Retention, and Influence of Interval on Eye and Arm Movement; W. G. SMITH, Mind, N.S., iii, Conditions of Retention; BARTH, Diss. Dorpat (1894), Ortssinn; BOLTEN, Amer. J. of Psychol., iv, Digit Series read and written; KIRKPATRICK, Psychol. Rev. i, Objects, and Written and Spoken Words; LEWY, Zeitsch. f. Psychol., viii, Measurement of Visual Area, and Haptic Localization; JACOBS and BRYANT, Mind, O.S., xii. 75, 'Span' of Memory; WARREN and BALDWIN, Proc. Amer. Psychol. Assoc., ii (1893); BALDWIN and SHAW, Psychol. Rev., ii. 236; WARREN and SHAW, Psychol. Rev., ii. 239 (the last two citations are also in Princeton Contrib. to Psychol., i. 2), Visual Square Size; BINET, Introd. à la Psychol. expér. (1894), and Rev. Philos., xxxvii, Numerals, Lines, &c.; T. L. SMITH, Amer. J. of Psychol., vii, Muscular; SCHNEIDER, Diss. Dorpat (1894), Muscular; COHN, Zeitsch. f. Psychol., xv, Co-operation of Partial Memories; PHILIPPE, Rev. Philos., 1897, Images of Objects; WOLFE, Amer. J. of Psychol., ix, 1898, Size of Objects, &c.

(2) Recognition, Identification, Selection, Comparison: E. H. WEBER (1846), Visual Lengths and Weights; WOLFE, Philos. Stud., iii, Tones; LEHMANN, Philos. Stud., v, Grays and Scents; MÜNSTERBERG, Psychol. Rev., i, Colours and Numbers in Duplicate Series; BIGHAM, Psychol. Rev., i, Visual and Auditory Stimuli, Effect of Filled and Empty Intervals; BALDWIN, SHAW, and WARREN, Princeton Contrib. to Psychol. (also as cited above), i (1895), Visual Square Size; SCHUMANN, Zeitsch. f. Psychol., i, Series of Sounds; LOEWENTON, Diss. Dorpat (1893), Position on the Skin; RADOSLAWOW-HADJI-DENKOW, Philos. Stud., xv, Visual Distances. (E.B.T.- J.M.B.)

Memory Image: see IMAGE. The form 'Memorial Image' is not recommended. (J.M.B.- G.F.S.)

Memory Time: see REACTION TIME.

Mencius [Lat. form of Chinese Mung-tse: Mung, the philosopher]. (b. cir. 371 B.C.) With Confucius, one of the two greatest Chinese philosophers. See ORIENTAL PHILOSOPHY (China).

Mendelssohn, Moses. (1729-85.) Studied the Bible, the Talmud, and Maimonides with early zeal. Became (1750) tutor in a rich Jewish family in Berlin, and in 1754 book-keeper in the firm. Became an intimate acquaintance of Lessing. In 1763 received a prize from the Academy of Berlin. Died in Berlin.

Meninges: see MENINX.

Meningitis: Ger. Hirnhautentzündung; Fr. méningite; Ital. meningite. Diseased conditions of the membranes (see MENINX) investing the brain (leptomeningitis, pachymeningitis). Cf. BRAIN (Glossary). (H.H.)

Meninx [Gr. mhnigx, membrane]: Ger. Hirnhaut; Fr. méninge; Ital. meninge. One of the three membranous envelopes of the central nervous system. It is chiefly used in the plural (meninges) and in composition. Cf. BRAIN. (H.H.)

Mental Blindness and Deafness: see BLINDNESS, and DEAFNESS (mental or psychic).

Mental Chronometry: see REACTION TIME.

Mental Development: Ger. seelische Entwickelung; Fr. développement mental; Ital. sviluppo mentale. The series of processes through which the individual mind naturally passes from birth to death.

Development is here, as in its biological use, contrasted with EVOLUTION (mental, q.v.). It is the ontogenetic as contrasted with the phylogenetic mental process. The questions which come up in connection with mental development are those of one branch of GENETIC PSYCHOLOGY (q.v.) as contrasted with analytic psychology; that is, they are questions of the antecedents of mental states and of the laws of change from one stage of mental life to another. In general, the distinction is analogous to that between morphology and physiology. Certain questions, however, as in biology, belong to the genetic as such, and involve the relation of development to evolution; see RECAPITULATION, REGRESSION, ATAVISM, VARIATION. Among the problems peculiar to mental development, on the other hand, some of the more important are: the genetic relation of the motor to the sensory processes; the original forms of consciousness, with the ultimate modes which its process takes on; the law of the relation of mind to its environment, both physical and social; the relation of instinctive endowment to acquisition and GROWTH (q.v.); the methods of mental ACCOMMODATION (q.v.); HABIT (q.v.) and its relation to accommodation; the interaction of the primary functions and the order of the appearance of the relatively new stages which each of them successively assumes; the tracing of the constant factors, and their relation to the variations which introduce new departures, &c. Most of the problems of philosophical biology, in fact, find analogies in mental evolution and development; and in many cases the psychological solution is necessary to the biological solution, since the problem is really one with two faces.

Certain departments of the subject have been marked off in recent years and in part developed. We have CHILD PSYCHOLOGY (q.v.) treated as a more or less separate subject, and SOCIAL PSYCHOLOGY (q.v.) similarly. The influence of the genetic point of view is permeating more and more the treatment of general or analytic psychology. It is being seen that analysis is never adequate if it be purely dissection, for the actual statement of mental process must include more or less change and development. Mental development in the animals is treated in COMPARATIVE PSYCHOLOGY (q.v.).

Literature: BIBLIOG. G, 1, e, f; titles given under the topics cited above; Psychological Index, in loc., 1 ff. Of recent works, JODL, Lehrb. d. Psychol., and STOUT, Manual of Psychol., are written from a genetic point of view. BALDWIN'S Ment. Devel. (2 vols.) is devoted explicitly to this subject proper and to EVOLUTION (mental, q.v.). (J.M.B., G.F.S.)

Mental Disease: see PATHOLOGY, and the various special names of mental disorders. Cf. PSYCHOSIS, and NEUROSIS.

Mental Energy: see ENERGY (ad fin.), and cf. SOCIAL LOGIC.

Mental Evolution: see EVOLUTION (mental).

Mental Pathology: see PATHOLOGY (mental).

Mental Science: see PSYCHOLOGY, and cf. MORAL SCIENCES.

Mental Type: see TYPE (mental).

Mental Unity: Ger. Einheit des Bewusstseins; Fr. unité de la conscience, unité du moi; Ital. unità della coscienza. The apparent oneness of the individual mind.

Theories of mental unity are abundant both in psychology and in metaphysics. The three most prominent theories are: (1) the intuitional, which holds not only to the psychological immediacy of the consciousness of unity, but also to its rational validity as a datum of thought; (2) the empirical theory, which makes the consciousness of unity an experiential product: that is, it denies that it is psychologically IMMEDIATE (q.v.), although admitting that it is psychically so; (3) genetic theories, which hold that unity is the form of organization of conscious contents at any state of mental development; not a constant datum or a content at all, but a changing aspect of conscious process. On this view the unity of effort (conation) is different from the unity of feeling or cognition. A newer view under this head finds mental unity in the consciousness of the motor dispositions or habits which represent practical accommodations, or adjustments of attention.

Conscious unity is often confused with consciousness of self. But so far as self is a content, it has, rather than is, unity. Only the theory which makes the subject-self, or I, the form of organization of knowledge could identify this with the consciousness of unity.

The organization theory of the consciousness of unity is supported by the cases known as dual or MULTIPLE PERSONALITY (q.v.), in which division of the content of consciousness results in the appearance of different quasi-personalities, each with its own consciousness of unity. (J.M.B., G.F.S.)

Besides the holders of the intuitional theory mentioned above, many idealistic writers find in the consciousness of unity an a priori form or prerequisite to all experience, and argue to a noumenal or transcendental principle of unity, a soul or self. The scholastics made unity and simplicity attributes of the  soul. Descartes' 'cogito ergo sum' is followed by Kant's 'ich denke,' a principle of the 'transcendental unity of apperception' -- a function of the transcendental self. Cf. KANT'S TERMINOLOGY (glossary). Kant holds, as to empirical unity, however, that the identity of consciousness is only a formal condition of thought, and does not prove the numerical identity of the subject (Third Paralogism).

In later philosophy, Leibnitz's MONAD (monoV, one) and Herbart's REAL are principles of unity (see those terms). Lotze finds in mental unity in the midst of change the category (M) of explanation of the world. Indeed, most spiritualistic and idealistic philosophy is from the start an interpretation of experience and of the world as a system in some way resting upon mental unity. Cf. the psychological conceptions INDIVIDUAL, and IDENTITY.

Literature (psychological): appropriate passages in the psychologies; ARDIGO, L'Unità della Coscienza, Op. Filos., vii. (1898); MAUDSLEY, Mind, xvi. 161; citations from German authors in EISLER, Wörterb. d. philos. Begriffe, 'Einheit'; works on metaphysics generally. (J.M.B.- K.G.)

Mentality [Lat. mens, mind]: Ger. psychische Beschaffenheit; Fr. mentalité; Ital. mentalità. The distinctive characteristics of mind or conscious life abstractly considered. (G.F.S.- J.M.B.)

Applied particularly to the different grades of mental endowment, as exhibiting more or less (higher or lower) mentality. Cf. SUBCONSCIOUS. (J.M.B.)

Mercantile System: Ger. Mercantil-system; Fr. système mercantile; Ital. sistema mercantile. A group of theories as to material wealth which prevailed in the 17th and 18th centuries, and under which the BALANCE OF TRADE (q.v.) was made a criterion of gain or loss in such wealth.

The best known writers of this school are perhaps Mun (1664), Petty, and Stewart. The most successful practical exponent was the French financier Colbert.

The mercantile theory has the merit of being the first system of political economy developed. Its fundamental error lies in mistaking a balance of sales and purchases for the real criterion of increase of wealth. An individual or a nation which tries to buy as little as possible is pursuing a miserly policy. The gold may be worth less than the things the gold will buy. Not diminution of purchases, but increase of investments is the true criterion of excess of production over consumption.

Literature: SMITH, Wealth of Nations, Bk. IV; COSSA, Introd. to the Study of Polit. Econ. (A.T.H.)

Mercy [Lat. merces, reward]: Ger. Gnade; Fr. grâce; Ital. pietà, misericordia. The trait of character which tends to mitigate the penalties which may be exacted for offences against law. Cf. PITY. (W.R.S.)

In theology: that attribute of the divine nature by virtue of which guilt is overlooked and a being who deserves punishment is treated with grace and kindness.

Mercy stands contrasted with justice in respect to merit and demerit. It is to be distinguished from love, which has no direct reference to desert. Mercy must also be distinguished from compassion (misericordia), which has direct reference to suffering rather than to ill desert. In the Christian scheme of redemption, mercy and justice are reconciled by the atonement of Christ, which cancels the claim of justice and gives free scope to the forgiving function of mercy.

Literature: see ATTRIBUTES (of God). (A.T.O.)

Merit [Lat. meritus, deserved]: Ger. Verdienst; Fr. mérite; Ital. merito. The degree in which an agent is worthy of approbation or reward in respect of his conduct. It is contrasted with demerit, which implies not only absence of merit, but liability to disapprobation or to punishment. See also GUILT.

The conception of merit is one of considerable difficulty in ethics -- largely from the intermixture of theological conceptions. From the purely moral point of view it is commonly held that merit belongs to the performer of all good or virtuous actions. Thus Butler says, 'Our sense or discernment of actions as morally good or evil implies in it a sense or discernment of them as of good or ill desert' (Diss. on Virtue). Sometimes merit is only ascribed when the good action is performed in spite of a temptation to evil; and the degree of merit is then said to vary with the strength of temptation overcome. Thus there is a tendency to restrict the application of the conception of merit to cases in which the motive is unselfish or even self-sacrificing. The tendency both of Calvinistic theologians and of many rationalistic moralists is to refuse to admit that merit can belong to human actions: a man can never do more than his duty. This is the position of the Stoics and of Kant.

The conception is more easily applied (though not more easily justified) when some external ground for deciding upon it is adopted. Thus the Utilitarian ethics regards meritorious actions as socially useful actions whose omission would not be punished, while their performance is rewarded by preferment or by good repute -- just as duties are held to be socially useful actions, the omission of which would be punished. (W.R.S.)

The distinctive characteristic of 'merit' is primarily claim to reward (or compensation for effort) as attaching to the conduct of a human being (or something else personified). But, as ethical ideas and sentiments grow more refined, it is recognized that for the highest merit the only appropriate reward is just the recognition of quality of goodness in the 'meritorious' conduct, together with emotional concomitants of such recognition -- love and admiration, and their expression in praise and gratitude. In this way, the notion of reward falling into the background, 'merit' comes to be hardly distinguishable from 'worth' -- which again is not distinguished from 'goodness' viewed especially as a quality admitting of degrees. See WORTH. (H.S.)

Merit (in theology). The surplus which may remain to the credit of any one in the sight of God after the strict claims of justice and obligation have been satisfied; a conception distinctive of, but not peculiar to Christian theology.

Merit may be either of Christ or of the saints. The merit of Christ is that credit with God which he acquires through his voluntary obedience to the law which man has broken. This merit constitutes a store of righteousness which may be imputed to the repentant and believing sinner for his justification. There is a radical difference of opinion regarding the question of the merit of the saints, between the Roman Catholic and Reformed Churches, the latter denying the possibility of any merit with God, while the former distinguishes between two kinds of merit, that of congruity and that of condignity; or relative and absolute merit. Only Christ himself can acquire absolute merit. But a man may by the grace of the Holy Spirit go beyond the strict measure of duty, and may acquire relative merit with God, which may under prescribed conditions be transferred to the credit of others. See SUPEREROGATION. (A.T.O.)

Mesenchyma [Gr. mesoV, middle, + egcuma, infusion]: Ger. Mesenchyma; Fr. mésenchyme; Ital. mesenchima. The non-epithelial portion of the mesoderm. In vertebrates the mesenchyma assumes at first the character of embryonic connective tissue, i.e. the scattered undifferentiated cells lie in a homogeneous matrix. During the further development of the embryo the mesenchyma becomes differentiated into a great variety of tissues: connective tissue proper, cartilage, bone, smooth muscle fibre, lymph-glands, spleen, &c.

The term was introduced by the brothers R. and O. Hertwig (see O. Hertwig, Entwickelungsgesch., 1st and 6th ed.). (C.S.M.)

Mesmer, Franz (or Friedrich) Anton. (1734-1815.) Educated at Dillingen, Ingolstadt, and (in medicine) Vienna. Began magnetic or 'mesmeric' treatment in 1772; moved to Paris (1778), where he was eminently successful. Practised in London with less success. A royal committee of eminent French scientists pronounced unfavourably as to his methods in Paris. Gave the name mesmerism to the phenomena now designated hypnotism.

Mesmerism: see MESMER, HYPNOSIS, and HYPNOTISM.

Meso- (in compounds) [Gr. mesoV, middle]: Ger. Mittel-; Fr. méso-; Ital. meso-. Of medium size or position between extremes; as mesocephalic, having a head of medium length. Cf. INDEX (cephalic). (J.J.)

Mesoblast [Gr. mesoV, middle, + blastoV, germ]: Ger. Mesoderm, mittleres Keimblatt; Fr. mésoblaste, feuillet moyen; Ital. mesoblasto (or mesoderma). This term, which is practically synonymous with mesoderm, was introduced by F. M. Balfour, and is used chiefly in England. See EMBRYO, and MESODERM. It has been used with other special meanings by German writers. O. Hertwig employs it as a synonym of mesothelium; others have applied it to the parent cells of the mesoderm. These latter usages have never become current.

Literature: FOSTER and BALFOUR, Introd. to Embryol. (1st ed.); F.M. BALFOUR, Compar. Embryol. (1881). See also MESODERM. (C.S.M.)

Mesoderm [Gr. mesoV, middle, + derma, skin]: Ger. Mesoderm, mittleres Keimblatt; Fr. mésoderme, feuillet moyen; Ital. mesoderma (or foglietto mediano). The middle germ-layer, or that germ-layer from which are derived those tissues which are not developed from the ectoderm on the outside or the endoderm on the inside.

It develops later than the ectoderm and endoderm, and may arise from either or both of these primary layers. It very early differentiates itself into two primary tissues -- MESENCHYMA, and MESOTHELIUM (q.v.).

The middle germ-layer was first clearly recognized by von Baer (1829), who called the outer sheet Fleischschicht, the inner sheet Gefässschicht. Remak gave the final demonstration that these two sheets are parts of a single germ-layer.

Literature: C. E. VON BAER, Entwickelungsgesch.; REMAK, Untersuchungen über die Entwickelung d. Wirbelthiere (1850-5); MINOT, Human Embryol., 166; and the literature of EMBRYOLOGY (q.v.). (C.S.M.- E.S.G.)

Mesognathous (Skull): see PROGNATHISM.

Mesothelium [Gr. mesoV, middle, + qhlh, a nipple]: Ger. Mesothel; Fr. mésothélium; Ital. mesotelio. Applied by Minot to the epithelium lining the primitive body-cavity of the embryo. It includes all the non-mesenchymal portions of the MESODERM (q.v.). During the embryonic period the mesothelium is differentiated into the permanent lining of the body-cavity, into the so-called segments from which the striated muscles arise, and into the rudiments (Anlagen) of the urogenital system.

The word is indefensible etymologically, but is a convenient addition to the terms derived from qhlh. Epithelium was first introduced as a name for the layer covering the nipple, and its application was soon extended to all layers conforming to the same type of histological structure, and in this wide sense epithelium is now universally used. Endothelium was introduced by His for epithelia lining all internal cavities, and similarly mesothelium was introduced by Minot for the epithelium lining the body cavity and derived from the middle germ-layer. These epithelia constitute morphologically a distinct group of tissues. (C.S.M.)

Messiah [Heb. Mashiah, from mashah, to anoint]: Ger. Messias; Fr. Messie; Ital. Messia. The name used in the Hebrew Scriptures to designate the promised Redeemer of the Jewish nation, who was to come in the fullness of time and deliver his people from all their temporal and spiritual enemies. The Messiah is the Christos of the New Testament and was identified with Jesus as the promised Saviour.

The Messiah was the child of promise and covenant engagement. Of the seed of Abraham and the stock of David, he was to unite in his person the threefold offices of prophet, priest, and king, and was to reign over an actual theocracy. The idea of the Messiah has a marked development in the Old Testament. At first he is to be merely a temporal deliverer, but in the later prophets he has assumed more than human proportions, and is represented as the spiritual redeemer of his people. Jesus Christ as the Messiah stands as the spiritual regenerator and Saviour of humanity. (A.T.O.)

Messianic Hope: Ger. Hoffnung auf den Messias; Fr. espérance messianique; Ital. aspettazione messianica. The expectation of the Jewish people, nourished by covenant promise and prophecy, of a golden age of material and spiritual prosperity under the personal reign of a MESSIAH (q.v.), who should unite in himself the offices of prophet, priest, and king.

The Messianic hope was the inspiring motive of Old Testament prophecy and the persistent ideal which gave unity to Jewish history. It was the kindler of an inextinguishable aspiration which has been able to survive even the rejection of Christ and is entertained by at least a portion of the Jewish people at the present day. What is called Reformed Judaism has dropped the Messianic feature from its creed.

Literature: BRIGGS, Messianic Prophecy; ORELLI, Old Testament Prophecy; DELITZSCH, Messianic Prophecy, &c.; DRUMMOND, The Jewish Messiah (1877); A. EDERSHEIM, Prophecy and Hist. in relation to Messiah (1885). (A.T.O.)

Metabolism [Gr. metabolh, a change]: Ger. Metabolismus, Stoffwechsel; Fr. métabolisme, échanges nutritifs; Ital. metabolismo. The sum of the changes, constructive and destructive, which go on in living bodies.

Food material, on the one side, is built up to form living protoplasm of muscle, gland, nerve, or other tissue. This constructive phase of metabolism is termed ANABOLISM (q.v.) or ASSIMILATION (q.v.). On the other hand, living protoplasm, in the process of breaking down into simpler, dead compounds, yields the energy by which the organism does its work, these processes being grouped under the term KATABOLISM (q.v.). 'Assimilation and disassimilation, or anabolism and katabolism, go hand in hand, and together constitute an ever-recurring cycle of activity, which persists as long as the material retains its living structure, and which as a whole is designated under the name metabolism' (Howell's Textbook, as below).

Metabolism of plants, aided by the energy of sunlight, is chiefly anabolic, constructing inorganic substances into living protoplasm, or into proteids, carbohydrates, and fats. Animal protoplasm, on the other hand, is chiefly katabolic, turning these food materials to simpler compounds, principally to water, carbonic acid, and urea.

Literature: the textbooks of physiology, especially HOWELL, Amer. Textbook of Physiol. (C.F.H.)

Metagenesis [Gr. meta + genesiV, production]: Ger. Metagenese; Fr. métagenèse; Ital. metagenesi. A form of ALTERNATION OF GENERATIONS (q.v.) among invertebrates, chiefly among coelenterates and vermes. The term was introduced by Owen to mark the distinction from metamorphosis.

The essential facts of this phenomenon are the production of a first generation of individuals by the ordinary sexual processes, and the production of a second generation by asexual processes. Individuals of the second generation propagate sexually, but their offspring belong to types of the first generation. The relations are often further complicated: first, through the unlikeness of two generations in structure; second, through the increase in the number of asexual generations. For example: many jelly-fish deposit eggs, which develop into hydroid individuals, and these multiply by transverse division and produce medusoid individuals, like the original parent; tape-worms lay eggs, which produce the so-called larval young, and these multiply asexually (as in Coenurus), producing a second generation of sexually active tape-worms.

Literature: KORSCHELT and HEIDER, Entwickelungsgesch. d. Wirbellosen; PARKER and HASWELL, Zoology, i. See also under ALTERNATION OF GENERATIONS. (C.S.M.)

Metakinesis: see KINESIS, and MIND-DUST THEORY.

Metamere [Gr. meta + meroV, a part]: Ger. Metamer; Fr. métamère; Ital. metamero. A SEGMENT (q.v.) of the body. (C.S.M.)

Metamorphopsia [Gr. metamorfwsiV, change, + wy, eye]: Ger. Metamorphopsie; Fr. métamorphopsie; Ital. metamorfopsia (suggested -- E.M.). If a piece of the retina, through a wound or through some pathological condition, is detached from its normal situation and still retains its sensibility to light, the space-quale (surface-quale) of the light-sense will also be retained. The detached portion may have grown on again in a different place, or, since it is nourished chiefly from in front, it may continue to function for some time in spite of being detached (solutio retinae, detachment of the retina), although it is no longer in correct correspondence with the outer world nor with the space-reports of the other eye. Such errors of local sense are called metamorphopsiae. They occur also in the cutaneous local sense, if a piece of translocated skin retains its vitality -- as it may do when it is not entirely cut off, but rotated about a narrow non-detached portion as a stem. Both in the case of the skin and in that of the retina, a correct local sense is gradually recovered. This has been taken as showing that the spatial attribute of the visual sense is not direct, but indirect; if we saw yellow where we should see green, we could not educate ourselves into thinking that the sensation was green; it is only in the case of a sensation entering consciousness merely as a sign for another sensation that re-education is possible. More recent observations show, however, that in the case of the skin there is no retention of space-sense unless the connecting stem of skin is retained; hence the old space-sense may be preserved by means of nerve-fibres which pass through this stem, and the new may be regained only after the new nervous connections have grown up. But this view would not seem to take account of the retinal cases, for there the nervous connections grow out from the front, and have not been, at least in cases of solutio retinae, broken off at all, and hence the recovery (not the error) would here be difficult to account for, except when it can be supposed that the retina has returned to exactly its original position. The subject is in much need of careful revision, as it has been made a crucial feature in theories of the space-sense. Wundt himself has experienced the distortion in one of his eyes.

Literature: WUNDT, Physiol. Psychol. (4th ed.), ii. 102; LEBER, in Graefe u. Saemisch, Handb. d. Augenh., v (2), 612, 619, and literature there given; STRANSKY, Biol. Centralbl. (1900). (C.L.F.)

Metamorphosis [Gr. meta, change, + morfh, form]: Ger. Metamorphose; Fr. métamorphose; Ital. metamorfosi. A considerable change of form, sufficient to affect its general appearance and characteristics, occurring more or less abruptly during the development of an individual.

The change of a LARVA (q.v.) into a CHRYSALIS (q.v.), or of a chrysalis into an IMAGO (q.v.), is a metamorphosis. The term is not applied to a gradual transformation, as of the embryo into an adult. (C.S.M.)

Literature: SEDGWICK, Zoology; PACKARD, Entomology; COMSTOCK, Entomology; LUBBOCK, Origin and Metamorphoses of Insects (1874); F. M. BALFOUR, Compar. Embryol. (1881); D. SHARP, art. Insecta in Camb. Nat. Hist. (C.S.M.- E.S.G.)

Metaphysics [Gr. meta + fusika, things physical or natural]: Ger. Metaphysik; Fr. métaphysique; Ital. metafisica. Owes its name to the editorial arrangement of Aristotle's treatise on the subject by Andronicus of Rhodes (cir. 63 B.C.), who placed it after the treatise on physics, with the general superscription ta meta ta fusika. Aristotle's own name for the discussions contained in it was 'First Philosophy' or 'Theology,' and from his description of them as concerned with the nature of 'being as being,' the later term ONTOLOGY (q.v.) was coined. The name Metaphysica first appears -- as a singular noun -- in Averroes and the scholastics of the 13th century.

The term has proved an unfortunate one, as suggesting that the science is divorced from experience and concerned altogether with the transcendent. Kant is responsible for spreading this idea of metaphysics by his repeated descriptions of it as a science of assertions about the transcendent, a science, moreover, involved in a series of inevitable self-contradictions. He certainly had historical ground for his strictures upon the old metaphysic, if we take Wolff's definition of it as 'the science of all that is possible, so far as it is possible' -- a science supposed to be evolved by analysis from the logical principle of identity or contradiction. Metaphysics was divided by Wolff into a general part (ontology), which treats of the most abstract determinations of being in general, whether corporeal or spiritual, and three special parts (rational cosmology, rational psychology, and rational theology), named according to their principal subjects (the world, the soul, and God). These latter disciplines form the subject of Kant's attack in the Dialectic, and in contrast with the Wolffian metaphysics he gives his own idea of the science of metaphysics, as the only science which admits of completion: 'This science is nothing more than the inventory of all that is given us by pure reason, systematically arranged.' To this science the Critique, as the doctrine of the limits of pure reason, was designed to form an introduction. According to this Kantian usage, metaphysics would become synonymous with EPISTEMOLOGY (q.v.) or with a part of that science.

Wolff's system represents, however, neither the best modern nor the old Aristotelian conception of philosophy. Metaphysics, as the central philosophical discipline, might rather be defined as simply the systematic interpretation of experience and the explication of all its implicates. The implicates of experience cannot be described -- in any condemnatory sense at least -- as 'beyond' experience; although, doubtless, the result of metaphysical analysis may be to show the impossibility of identifying experience with the isolated particulars of sensationalistic philosophy. If experience be taken without any such arbitrary limitation of its meaning, metaphysics seeks simply to harmonize or rationalize experience, i.e. to exhibit it as a system or interconnected whole. Metaphysics, as William James pithily puts it, 'means only an unusually obstinate attempt to think clearly and consistently' (Textbook of Psychol., 461); or, as Plato expressed it, it is the effort to think things together -- not in isolation and abstraction, but in relation to one another, and as parts or aspects of one concrete whole. The different sciences are all 'abstract,' because each starts with certain presuppositions or working postulates which give true results within the limits of the science itself, but which are found on critical examination to be full of obscurity and contradiction, if offered as true in the full sense of that term, namely, as giving a finally intelligible explanation of the experience in question. Metaphysics aims at correcting the abstractions of the different sciences, and relating them to one another, reaching thereby an expression of the concrete truth of experience as such. The truth, however, which metaphysics seeks to reach -- even when presented under the questionable designation of absolute truth -- does not really transcend experience in any other sense than that in which the whole transcends its parts.

Metaphysics, in this sense, must obviously coincide to a large extent with epistemology, conceived as 'criticism of categories,' or with logic in the Hegelian sense; and accordingly the most convenient usage (and that most in harmony with the history of the term) is probably to regard metaphysics -- the theory of knowing and being -- as the wider term, including as its two subdivisions or aspects epistemology and ontology. The latter term would then be used to signify what is the culmination of metaphysical effort, a synthetic statement in ultimate terms of the nature of the real, so far as that is attainable from the human standpoint. But the disuse of the term ontology in current philosophical writing has led to a considerable variety of usage in regard to the term metaphysics, which is still further increased, of course, by the divergences of philosophical creed in the writers. Many writers of positivistic and Neo-Kantian tendencies, attaching to metaphysics the old associations of transcendency, deny the possibility of the science, and put epistemology, or analysis of conceptions, in its place. Others, on the contrary, Hegelian in general tendency, associate epistemology solely with subjectivistic attempts, of a Kantian or sceptical kind, to pronounce on the validity of thought as such, and deny in consequence the possibility of such a science; but they would apparently apply the term metaphysics to an analysis of conceptions much resembling what the former set of writers include under the head of epistemology. Among recent English writers, it may be noted that both Shadworth Hodgson and Laurie use metaphysics very nearly as equivalent to epistemology, but the former finds it necessary to supplement this investigation by what he calls 'the constructive branch of philosophy' (cf. Philos. of Reflection, chap. xi), while the latter indicates a distinction between this 'analytic,' or metaphysic considered as a demonstrative science, and what he calls 'speculation' or 'a synthetic cosmic construction on the basis of the preceding analytic' (cf. Met. Nova et Vetusta, 284, 2nd ed.). Perhaps the commonest usage at the present day, and one that has much in its favour, is to use metaphysics in a narrower sense as opposed to epistemology, in which case it corresponds with the definition of ontology given above. In this sense it is used, for example, by Paulsen, Külpe, and Volkelt, the most recent authors of Introductions to Philosophy. Külpe points out that if the analysis of knowledge and its conceptions be excluded from its sphere, there still remains as the task of metaphysics proper 'the development of a Weltanschauung.' In essaying this task, he proceeds, metaphysics is based upon practical motives on the one hand, and, on the other, upon the demand for a completion of scientific knowledge which shall be free from contradictions. In a sense, any such view of the world as a whole may be said to transcend the fragmentary data at our disposal. Within the domain of the sciences, which start from certain hypotheses, demonstration and verification of particular propositions may be possible, on the assumption of these hypotheses; but metaphysics, in rising to its supreme hypotheses or postulates, can obviously never hope to offer demonstration or verification in the same sense. It is one thing, as Volkelt puts it, 'to postulate supreme principles of a certain nature, that is, starting from the facts of experience to declare that the solution of certain problems can lie only in the direction of certain fundamental thoughts; it is something quite different to exhibit everything individual as arising, so to speak, out of the highest principles, and explainable from the inner necessity of these principles.' In very similar words, at the conclusion of his Metaphysics, Lotze expresses his profound conviction of 'the living and active meaning of the world,' but adds: 'We do not know this meaning in its fullness, and therefore we cannot deduce from it what we can only attempt, in one universal conviction, to retrace to it.' This is, indeed, the main difference between the pretentious metaphysics of the Wolffian type and the more modest attitude of present-day thinkers. (A.S.P.P.)

If the last-mentioned usage be adopted -- which seems advisable -- we have the term PHILOSOPHY (q.v.) to include both epistemology and ontology (metaphysics).

Literature: that of philosophy generally, see BIBLIOG. B, 1, c; also for special periods and authors, BIBLIOG. A, 1, 2; see also the Histories of Philosophy, and the Introduction to Philosophy (BIBLIOG. A, 1, and B, 1 a). For contemporary works see the annual lists issued by the Arch. f. system. Philos., 1 ff. Other bibliographies are listed in the vol. (iii) of bibliographies, GENERAL, 1. (J.M.B.)

Metapsychosis: see TELEPATHY.

Metayer System [Med. Lat. medietarius]: Ger. Halbpachtsystem, Metawirthschaft; Fr. métayage; Ital. mezzadria. Farming on share rent; especially in those countries where the class of mediarii has had a continuous existence. The share is not necessarily one-half; in Tuscany, as a rule, the metayer receives two-thirds.

In England the commutation of the feudal labour dues was made into a small fixed money payment, which put the occupier almost into the position of an owner. In the Romance countries the change was not so complete; and in Italy, specifically, the nobles were powerful enough to insist on the receipt of shares of the produce, which left the cultivator far short of a position of independence. (A.T.H.)

Metazoon [Gr. meta + zwon, an animal]: Ger. Metazoon; Fr. métazoaire; Ital. metazoo, metazoario. An animal consisting of several or many cells differentiated into tissues as opposed to a protozoon, which consists of a single cell.

The term was introduced by Haeckel in his Generelle Morphologie, 1867. It includes all animals excepting the Protozoa. (C.S.M.)

Metempirical [Gr. meta + empeiria, experience]: Ger. metempirisch; Fr. métempirique; Ital. metempirico. A term due to George Henry Lewes, and used by him in a sense almost exactly equivalent to the Kantian use of transcendent -- that which is not verifiable within the bounds of possible experience.

'Since we are to rise to metaphysics through science, we must never forsake the method of science; and further, if in conformity with inductive principles we are never to invoke aid from any source higher than experience, we must, perforce, discard all inquiries whatever which transcend the ascertained or ascertainable data of experience. Hence the necessity for a new word which will clearly designate this discarded remainder -- a word which must characterize the nature of the inquiries rejected. If, then, the empirical designates the province we include within the range of science, the province we exclude may fitly be styled the metempirical' (Lewes, Problems of Life and Mind, 1st series, 16). In Barratt's Physical Metempiric the term is used in a wider sense, which makes it include whatever cannot literally become part of the subjective experience or consciousness of any given person. In this sense it is made to include the existence of other conscious persons who are, in Clifford's phrase, 'ejects' or mental constructs to explain certain features of subjective experience, not themselves parts of that experience as a psychical process. But the current sense of the term is that attached to it by its inventor. (A.S.P.P.)

Metempsychosis [Gr. meta + emyucoun, to animate]: Ger. Metempsychose, Seelenwanderung; Fr. métempsycose; Ital. metempsicosi, transmigrazione. The transmigration of the soul from one bodily form, human or animal, into another.

This is one of the earliest forms in which the doctrine of the immortality and pre-existence of the soul appears, and is probably connected with the primitive theory of a kinship or blood-relationship between man and beasts (cf. Burnet, Early Greek Philos., 100). Herodoctus (ii. 123) derives the belief from Egypt: 'The Egyptians are the first who propounded the theory that the human soul is immortal, and that when the body of any one perishes, it enters into some other creature that may be born ready to receive it, and that when it has gone the round of all created forms in land, in water, and in air, it once more re-enters a human body born for it; and this cycle of existence takes place in 3,000 years.' Metempsychosis is one of the best-authenticated parts of the teaching of Pythagoras, with whose name it has continued to be specially associated. Plato does not exactly teach the doctrine dogmatically, but avails himself of it in the mythical presentations of his thought. By him it is connected with a law of moral retribution. The details vary, and it is difficult to say how far any of them are taken seriously by Plato (cf. Phaedrus, 249; Republic, x. 614 f.). In the myths of the Gorgias and the Phaedo the doctrines does not appear. (A.S.P.P.)

Besides its prominence in Orphic, Pythagorean, and Egyptian teaching, metempsychosis is a tenet of Indian, Jewish (Cabbala), and Swedenborgian philosophy. It is interesting to note a tendency in current discussion of the immortality of the soul to recur to the hypothesis of pre-existence, as following from the arguments which are urged in support of post-mortem personal existence. The poetry of Plato's doctrine of 'reminiscence' (anamnhsiV) reappears also, as in Wordsworth's Intimations of Immortality. Yet it is difficult to call that a future life in any vital sense which is thought of as being disconnected with this life, as this is with a possible earlier life.

Literature: see IMMORTALITY, and ORIENTAL PHILOSOPHY. (J.M.B.)

-meter (apparatus ending in): see LABORATORY AND APPARATUS, III, E.

Method [Lat. methodus; Gr. meqoduV, from meta + odoV, way]: Ger. Methode; Fr. méthode; Ital. metodo. See the topics immediately following; also PSYCHOPHYSICAL METHODS, and SCIENTIFIC METHOD.

Method and Methodology, or Methodeutic: Ger. Methodenlehre; Fr. méthodologie, théorie de la méthode; Ital. teoria dei metodi, metodologia. A branch of logic which teaches the general principles which ought to guide an inquiry.

Owing to general causes, logic always must be far behind the practice of leading minds. Moreover, for the last three centuries thought has been conducted in laboratories, in the field, or otherwise in the face of the facts, while chairs of logic have been filled by men who breathe the atmosphere of the seminary. The consequence is that we can appeal to few works as showing what methodology ought to be. The first book of Bacon's Novum Organum is well enough, as far as it goes, and was no doubt useful in its day. Senebier's L'Art d'observer is instructive. Comte's Philosophie positive accomplished something. Whewell's History of the Inductive Sciences and other works have the advantage of being written by a man of great power of investigation himself, who drew his doctrine from the facts of scientific history. Mill's System of Logic is, no doubt, of considerable value, although the author knew too little of science. There is hardly one of the illustrations of fine method adduced in his first edition which has not been refuted. Beneke's Logik in praktischer Absicht was not altogether without value. Of great value, also, is Jevon's Principles of Science. Pearson's Grammar of Science is a work of great force, but unfortunately too much influenced by certain philosophical ideas. Wundt devotes two of the three volumes of his Logik to Methodenlehre.

The traditional doctrine of method is confined chiefly to rules of definition and division, which teach an exactness of thought much needed, but are marked by the total absence of modern ideas. Cf. SCIENTIFIC METHOD, and EVIDENCE. (C.S.P.)

Method (in education). An orderly procedure in teaching; a systematic way of teaching and training.

Methods of teaching depend, in a last analysis, upon the acts of mind involved in sense experience and thought. First impressions are prone to inadequacy and even incorrectness. They must be reinforced by drafts upon the stored-up experience of the mind -- anticipations of what we may look for in the complete identification of the object. After objects are fully identified, we seek to find their universal properties. In thus making the complete survey of an object of knowledge three steps are involved: (a) preliminary apperception or identification; (b) reinforcement of present by past experience; (c) advance to generalization. In acquisition, therefore, three things are involved: namely, apperceptive identification, deductions of anticipations for further identification, generalization by inductive processes. These are the essential steps of an adequate method. They may be recognized in the terms observation, deduction, induction. When the emphasis is laid on the first, we have the so-called method of observation; when on the second, that of deduction; when on the third, that of induction.

The variety and combination possible in these fundamental stages of method are numerous. Thus, if we arrive at generalizations through catechetical means, we speak of the Socratic method. The Herbartians emphasize (1) the apperception of observed facts, (2) the inductive approach to generalization, (3) the deductive application of these generalizations to appropriate new particulars. From the standpoint of the teacher, we have the lecture method (the monologue); the developing, catechetical or Socratic method (the dialogue). With regard to the thing learned, we may begin with the whole and proceed to the parts (analytical method), or we may begin with the parts and proceed to the whole (synthetical method). In either of these cases the three fundamental stages (observation, deduction, and induction) are to be traced. With regard to the learner, knowledge must be acquired in accordance with the fundamental forms of thought, which are (1) the conception, (2) the judgment, (3) the syllogism.

Most Herbartian writers name what they conceive to be five essential stages or steps in a correct method, as follows: --

(1) Preparation. This consists of a brief preliminary review of such acquired knowledge or experience as will best fit the child's mind for a rapid and interested appropriation of the new matter about to be presented. (2) Presentation of the new lesson. (3) Association. This stage provides for more complete apperception of the facts of the new lesson, by associating them intimately with related facts already acquired. (4) Generalization. This stage gathers up the facts of the lesson in such a manner that their deeper inner significance may be grasped by the pupil. In many studies these generalizations appear in the form of definitions, rules, principles, laws, maxims, &c. (5) Application. By this stage is meant those drill and practical exercises which tend to fix knowledge in mind, and to secure a facile application of it to practical affairs. As may easily be seen, these stages are but an amplification of observation, deduction, and induction, the three logical steps found in all experience and thinking.

Literature: BAIN, Educ. as a Sci., 230-357; ROSENKRANZ, Philos. of Educ., 90-105; HERBART, Sci. of Educ. (trans. by Filkin), 154-86; TOMPKINS, Philos. of Teaching, 73-275; McMURRY, The Method of the Recitation; DE GARMO, Essentials of Method. (C.DE.G.)

Methods of Ethics: Ger. Methoden der Ethik; Fr. méthodes de morale; Ital. metodi dell etica. The rational modes of procedure for determining what is morally right or reasonable and what the reverse.

In his Methods of Ethics (1874) H. Sidgwick distinguishes the different methods which seem prima facie reasonable, and then develops and applies each so as to bring out the system of moral judgments to which it leads. He defines a 'method of ethics' as 'any rational procedure by which we determine right conduct or practice in any particular case.' The expression was given currency by him. (W.R.S.)

Methodeutic: see METHOD AND METHODOLOGY.

Methodical Selection. A term used by Darwin for a form of ARTIFICIAL SELECTION (q.v.). (J.M.B.)

Methodology: see METHOD AND METHODOLOGY.

Method-whole: Ger. methodische Einheit; Fr. (not in use); Ital. unità metodica (suggested -- E.M.) A portion of the subject-matter of instruction to which the formal steps or stages of instruction conveniently apply.

Herbartian writers on method advocate the subdivision of the subject-matter of instruction into minor wholes or unities, so that with each group there may be (1) the acquisition of new facts, (2) an inductive organization of these facts into general truths, and (3) a deductive application of the generalizations to new sets of allied facts. The aim of each group is the leading purpose for which it is taught; the stages in the treatment of the method-whole are the 'formal steps' of instruction. See METHOD (in education), and FORMAL STEPS.

Literature: ZILLER, Allg. Päd., 294; DE GARMO, Essentials of Method, chap. vi; McMURRAY, The Method of the Recitation, chap. xii. (C.DE.G.)

Metronymic (or Mat-) [Gr. mhthr, mother, + onoma, name]: Ger. metronymisch; Fr. métronymique; Ital. matronimico. (1) Noun. A name derived from the name or description of the mother or other female ancestor. (2) Adj. Applied to the female line of descent, marked by the perpetuation of mother names to the exclusion of father names. (3) Adj. Tracing descent through mothers, e.g. a metronymic clan.

(1) Used by Freeman (Norman Conquest, v. 380) to characterize certain personal names surviving in England before and after the Norman Conquest. (2) Used by Réclus (Primitive Folk, 157) of the early customs of Egypt. (3) Used in systematic sociology by Giddings (Princ. of Sociol.), instead of the term matriarchal. (F.H.G.)

Meyer's Experiment: Ger. Meyer'scher Versuch: Fr. expérience de Meyer; Ital. esperienza del Meyer. An experiment in visual contrast. Lay on a coloured field a small piece of grey paper, and cover the whole with white tissue-paper. The colour complementary to the field spreads over the grey. The vividness of the effect is due not to the diminution of saturation but to the blurring of the outline of the grey. Cf. CONTRAST (visual, simultaneous).

Literature: H. MEYER, Pogg. Ann. (1855), xiv. 170; HELMHOLTZ, Physiol. Optik (2nd ed.), 547; EBBINGHAUS, Psychologie, 221; SANFORD, Course in Exper. Psychol., expt. 152 c. (E.B.T.)

Meynert, Theodor. (1833-92.) Educated at Vienna. Privatdocent in brain anatomy, 1865; prosector of the Vienna Insane Asylum, 1866; director of the Psychiatric Clinic, and assistant professor of psychiatry in the University, 1870; professor of neurology, 1873; privy councillor, 1885. President of the Psychiatric Association, vice-president of the Vienna Medical Society, and member of the Imperial Academy of Sciences.