LEIBNITZ 421 absorption of both by Spinoza into the one divine substance, followed from an erroneous conception of what the true nature of substance is. Substance, the ultimate reality, can only be conceived as force. Hence Leibnitz s metaphysical view of the monads as simple, per cipient, self-active beings, the constituent elements of all things, his physical doctrines of the reality and constancy of force at the same time that space, matter, and motion are merely phenomenal, and his psychological conception of the continuity and development of consciousness. In the closest connexion with the same stand his logical principles of consistency and sufficient reason, and the method he developed from them, his ethical end of perfection, and his crowning theological conception of the universe as the best possible world, and of God both as its efficient cause and its final harmony. The ultimate elements of the universe are, according to Leibnitz, individual centres of force or monads. Why they should be individual, and not manifestations of one world-force, he never clearly proves. 1 His doctrine of individuality seems to have been arrived at, not by strict deduction from the nature of force, but rather from the empirical observation that it is by the manifesta tion of its activity that the separate existence of the individual becomes evident ; for his system individuality is as fundamental as activity. (i The monads," he says, " are the very atoms of nature in a word, the elements of things," but, as centres of force, they have neither parts, extension, nor figure (p. 705). Hence their distinction from the atoms of Democritus and the mate rialists. They are metaphysical points or rather spiritual beings whose very nature it is to act. As the bent bow springs back of itself, so the monads naturally pass and are always passing into action without any aid but the absence of opposition (p. 122). Nor do they, like the atoms, act upon one another (p. 680) ; the action of each excludes that of every other. The activity of each is the result of its own past state, the determinator of its own future (pp. 706, 722). " The monads have no windows by which anything may go in or out " (p. 705). Further, since all substances are of the nature of force, it follows that "in imitation of the notion which we have of souls" they must contain something analogous to feeling and appetite. It is the nature of the monad to represent the many in one, and this is per ception, by which external events are mirrored internally (p. 438). Through their own activity the monads mirror the universe (p. 725), but each in its own way and from its own point of view, that is, with a more or less perfect perception (p. 127) ; for the Cartesians were wrong in ignoring the infinite grades of perception, and identifying it with the reflex cognizance of it which may be called apperception. Every monad is thus a microcosm, the universe in little, - and according to the degree of its activity is the distinctness of its representation of the universe (p. 709). Thus Leibnitz, borrowing the Aristotelian term, calls the monads entelcchies, because they have a certain perfection (rl eWeA.es) and sufficiency (aiiTcipKfia.) which make them sources of their internal actions and, so to speak, incorporeal automata (p. 706). That the monads are not pure entelechies is shown by the ditl erences amongst them. Excluding all external limitation, they are yet limited by their own nature. All created monads contain a passive element or materia prima (pp. 440, 687, 725), in virtue of which their perceptions are more or less confused. As the activity of the monad consists in perception, this is inhibited by the passive principle, so that there arises in the monad an appetite or tendency to overcome the inhibition and become more perceptive, whence follows the change from one perception to another (pp. 706, 714). By the pro portion of activity to passivity in it one monad is differentiated from another. The greater the amount of activity or of distinct percep tions the more perfect is the monad ; the stronger the element of passivity, the more confused its perceptions, the less perfect is it (p. 709). The soul would be a divinity had it nothing but dis tinct perceptions (p. 520). The monad is never without a perception ; but, when it has a number of little perceptions with no means of distinction, a state similar to that of being stunned ensues, the monade nue being per petually in this state (p. 707). Between this and the most distinct perception there is room for an infinite diversity of nature among the monads themselves. Thus no one monad is exactly the same as another ; for, were it possible that there should be two identical, there would be no sufficient reason why God, who brings them into actual existence, should put one of them at one definite time and place, the other at a di fie rent time and place. This is Leibnitz s principle of the identity of imliscernilles (pp. 277, 755) ; by it his early problem as to the principle of individuation is solved by the distinction between genus and individual being abolished, and every individual made sui yrnrris. The principle thus established is formulated in Leibnitz s law of continuity, founded, he says, on the doctrine of the mathematical infinite, essential to geometry, and of importance in physics (pp. 104, 105), in accordance with which 1 Sec Considerations tur la doctrine J un efprit universel, 170i?. - Cf. Opera, ed. Omens, II. ii. ->0. there is neither vacuum nor break in nature, but "everything takes place by degrees" (p. 392), the different species of creatures rising by insensible steps from the lowest to the most perfect form (p. 312). As in every monad each succeeding state is the consequence of the preceding, and as it is of the nature of every monad to mirror or represent the universe, it follows (p. 774) that the perceptive con tent of each monad is in "accord" or correspondence with that of every other (cf. p. 127), though this content is represented with infinitely varying degrees of perfection. This is Leibnitz s famous doctrine of pre-established harmony, in virtue of which the infinitely numerous independent substances of which the world is composed are related to each other and form one universe. It is essential to notice that it proceeds from the very nature of the monads as per cipient, self-acting beings, and not from an arbitrary determina tion of the Deity. From this harmony of self-determining percipient units Leibnitz has to explain the world of nature and mind. As everything that really exists is of the nature of spiritual or metaphysical points (p. 126), it follows that space and matter in the ordinary sense can, only have a phenomenal existence (p. 745), being dependent not on the nature of the monads themselves but on the way in which they are perceived. Considering that several things exist at the same time and in a certain order of coexistence, and mistaking this con stant relation for something that exists outside of them, the mind forms the confused perception of space (p. 768). But space and time are merely relative, the former an order of coexistences, the latter of successions (pp. 682, 752). Hence not only the secondary qualities of Descartes and Locke, but their so-called primary qualities as well, are merely phenomenal (p. 445). The monads are really without position or distance from each other ; but, as we perceive several simple substances, there is for us an aggregate or extended mass. Body is thus active extension (pp. 110, 111). The unity of the aggregate depends entirely on our perceiving the monads com posing it together. There is no such thing as an absolute vacuum or empty space, any more than there are indivisible material units or atoms from which all things are built lip (pp. 126, 186, 277). Body, corporeal mass, or, as Leibnitz calls it, to distinguish it from the materia prima of which every monad partakes (p. 440), materia, sccunda, is thus only a " phenomenon bene fundatum " (p. 436). It is not a substantia but substantial or subftantiotwn (p. 745). While this, however, is the only view consistent with Leibnitz s fundamental principles, and is often clearly stated by himself, he also speaks at other times of the materia secunda as itself a composite substance, and of a real metaphysical bond between soul and body. But these expressions occur chiefly in the letters to DCS Bosses, in which Leibnitz is trying to reconcile his views with the doctrines of the Roman Catholic Church, especially with that of the real presence in the Eucharist, and are usually referred to by him as doctrines of faith or as hypothetical (see especially p. 680). The true vincutum substantiate is not the materia sccunda, which a consistent development of Leibnitz s principles can only regard as phenomenal, but the materia prima, through which the monads are individualized and distinguished and their connexion rendered possible. And Leibnitz seems to recognize that the opposite assump tion is inconsistent with his cardinal metaphysical view of the monads as the only realities. From Leibnitz s doctrine of force as the ultimate reality it follows that his view of nature must be throughout dynamical. And though his project of a dynamic or theory of natural philosophy was never carried out, the outlines of his own theory and his criticism of the mechanical physics of Descartes are known to us. The whole dis tinction between the two lies in the difference between the mechani cal and the dynamical views of nature. Descartes started from the reality of extension as constituting the nature of material substance, and found in magnitude, figure, and motion the explanation of the material universe. Leibnitz too admitted the mechanical view of nature as giving the laws of corporeal phenomena (p. 438), applying also to everything that takes place in animal organisms, 3 even the human body (p. 777). But, as phenomenal, these laws must find their explanation in metaphysics, and thus in final causes (p. 155). All thing?, he says (in his Specimen Dynamicum), can be explained either by efficient or by final causes. But the latter method is not appropriate to individual occurrences, 4 though it must be applied when the laws of mechanism themselves need explanation (p. 678). For Descartes s doctrine of the constancy of the quantity of motion (i.e., momentum) in the world Leibnitz substitutes the principle of the conservation of vis vim, and contends that the Cartesian position that motion is measured by velocity should be superseded by the law that moving force (vis matrix) is measured by the square of the velocity (pp. 192, 193). The long controversy raised by this criticism was really caused by the ambiguity of the terms employed. The principles held by Descartes and Leibnitz were both correct, though different, and their conflict only apparent. Descartes s 3 The difference between an organic and an inorganic body consists, he says, in this, that the former is a machine even in its smallest parts. 4 Opera, ed. Dutcns, iii. 321.
