From such lirokcn and dispersed lights his philosophy must be divined.
Leibnitz was essentially a Cartesian. He was Carte- sian in his method, and Cartesian in his fundamental principles. He never revolted from his great teacher. He pursued the Cartesian mode of analysis and abstrac- tion, he employed the Cartesian procedure by mathe- matical demonstration, he reasoned, like Des Cartes, from presumptive principles, he accepted the Cartesian indicia of truth; but he rendered them more precise, and was not wholly negligent of experience. He also rehabilitated the Scholastic or Aristotelian logic. He endeavored to combine with the dominant doctrine all that seemed valuable in elder systems, and he found some truth in all the schemes that he rejected. His imagination was too bold and too active to permit him to be the servile follower of anj^ master, and his perspi- cacity was too acute to overlook the fatal defects of the principles and conclusions of Des Cartes. The main errors to be corrected spnmg from the distinction made by the French reformer between mind and matter. Ac- cording to his theorj^, the one could not act upon the other. The intelligent and the material universe were thus hopelessly divorced. Mind was pure thought; matter was simjjle extension ; the apparent concurrence of the two in the phenomena of existence was due to divine assistancy. See Des Cartes. Beasts were ma- chines galvanized into the semblance of voluntary ac- tion by the intervention of divine power. PLvery move- ment was a nodus rindice dignus. If mind is pure thought, aU mental action must be an effluence, an ef- fect, or a manifestation of the one sole Intelligence. The distinction of minds was an impossibility. To Leibnitz the want of any princijnum indiriduutionis — that old war-cry of the schoolmeri — was apparent. He discussed this topic in a public thesis before he was sev- enteen (May 30, 1GG3, Opera, torn, ii, part i, p. 4(J0, ed. Dutens). He ascribed entitalive activity to matter, and a distinct entity to each individual mind. He regarded the human mind as an assemblage of dormant capacities {ivTi\i\tiai), to be called into action by the stimulation of sensations from without, and of promptings from within. He departed so far from the teachings of Des Cartes that he ascribed soul and reason to brutes, and in some sort to all matter also {Leihniiiana, § c. Opera, t. vi, part i, p. 315 ; comp. § clxxxi, p. 331 ; see Bayle, Diet. Hist. Crit. tit. Rorarius, Pereira). If matter is mere extension, it must be identical with space, and is " without form and void," impalpable, inconceivable, unreal. To give shape to " that which shape had none," motion must be recognised as an essential quality of matter, because form is produced by movement in space. Leibnitz at times goes so far as to suspect that all space is matter. For the production of motion, force — deter- minate power in action — is necessary. Of the real ex- istence of force the human consciousness affords assu- rance. From these corrections of the Cartesian postu- lates proceeded the mathematical and philosophical spec- ulations of Leibnitz in regard to vis viva, his Tluory of Motion, Abstract and Concrete, his Dynamics, and even his Calculus of Infinitesimals. All internal and external change, all properties and accidents of matter, are only "modes of motion." The latest science is returning to similar hypotheses, though the language of science is altered. Observed phenomena appeared to be contra- dicted by the definition of body, as the conjunction of ex- tension and motion. Bodies were often at rest, under- going no sensible change. Motion could not belong to them essentially as aggregates, but onlj' to the constitu- ents from whose conjoint operation the external or the internal movements of the mass proceeded. If a jiroper- ty was to inhere in such constituents, matter could not be infinitely divisible : the process of division must be ultimately arrested by reaching an irreducible atom :
" Fateare uecesse 'st, Esse en, quiE inillis jam prneditu partibus exstent, Et minima cousieut uatura."
LEIBNITZ
336
LiiiBNITZ
The motion attributed to these primordial particles is due to an indwelliii!? force. Thus, from liis definition of matter as the union of motion with extension, Leib- nitz was led to recognise as tlie iirlmary units of the universe an infinity of simple elementary substances or forces, which he designated jionads. These monads have some resemblance to those of Pythagoras, Democ- ritus, and Epicurus, and also to the Ideas of Plato ; but, unlike the Ei)icurean atoms, they are not solida, though they are (efenia. They are not material, but they are the souLs of matter. This vaporous dematerialization of matter may be illustrated by Plotinus's definition of matter by the successive segregation of all the proper- ties of specific body. Is not the theory of Boscovich, that matter is only an assemblage of points of force, an adaptation of Leibnitz's conception ? Has not the the- ory of Boscovich won atlmiration and hesitating ap- proval from manj' distinguished men of science?
The consequences of the rectification of the Cartesian conception of matter do not end here. As the motions or manifestations of force constitute the difference be- tween the several simple substances or monads, when there is no diversity of motion there is no difference of properties and no distinction of nature. Hence follows another dogma of Leibnitz, the Idenlitij of Indiscerni- bles. The monads are infinite in number, but they are unlilce, and present an infinite diversity of forces. There is also an infinite variety of gradations, from the lowest atoms of matter up through human souls to the supreme monad, or God. Each monad is in some sort the mirror of the universe of things; each possesses spontaneous energy or life within itself, and, in consequence of these characteristics, each has its own peculiar kind of reason, passive in matter unorganized, rudimentary in crystals and vegetable existence, unreflecting and instinctive in brutes, self-conscious and introspective in man, and as- cending through numberless orders of angelic intelli- gences. As motion is the principle oi quiddity ("the ghosts of defunct" terms must be evoked), force is an es- sential quality of all existence'; and is as imperishable as the monad is indestructible, unless both are annilii- lated by the same Power by which they were created. Here is another anticipation of recent scientific deduc- tions. As these forces are immutable, their separate spheres of action must be exempt from intrusion. There may be composition of motions, or equilibrium of an- tagonisms, but there can be no interaction or reciprocal influence.