ESTIMATE OF LEIBNIZ S PHILOSOPHY 159 



to the older philosophy for an explanation of the realities 

 themselves. Descartes has done well in clearing away 

 the great mass of forms, which explained nothing, and in 

 accounting for all the changes in nature by regarding 

 them as due to variations in the distribution of one 

 constant quantity of motion. But motion is not a deep 

 enough principle to explain reality. It is entirely apparent, 

 phenomenal, on the surface ; and therefore it cannot 

 explain that which is half-hidden, which comes and goes, 

 which passes from potentiality into actuality. But this 

 is the characteristic of every real thing, every res completa. 

 In so far as it exists, and is not merely possible, it has 

 come into being ; it is its nature to pass from potentiality 

 to actuality. We cannot have a better example of this 

 than the human soul, in which we find continuous process 

 along with unity and self-identity. Thus it seems to 

 Leibniz that real things or substances are to be conceived 

 as analogous to the human soul, as forms or living prin- 

 ciples in a sense deeper than that of the later Scholastics, 

 who had, indeed, almost entirely emptied the term 

 ' form ' of signification. Going back to the source of these 

 views that had so degenerated, Leibniz finds the nearest 

 approach to what he is seeking in Aristotle's ' entelechy, ' 

 the principle of a thing in the sense of its implicit perfect 

 realization, what it is in the thing to be or become. Thus 

 Leibniz supplements the Cartesian physics by the idea 

 that mere body or matter is an abstraction, existing 

 nowhere, and that every real existence has a soul or living 

 principle. And in this way the Monadology restores to 

 philosophy, with new force and meaning, the infinite 

 number of forms which was the chief feature of the 

 Peripatetic philosophy. 



Leibniz's relation to Atomist philosophy is for the most 

 part a negative one, and it is hardly necessary to add 

 anything to what has incidentally been said regarding it. 

 He is on the side of modern science in rejecting the idea 

 of an absolute vacuum. And when he sometimes speaks 



