OF THE UNITY OF THOUGHT. 713 



mere summation of separate elements or factors, and in 

 this way he introduces into the mental process a feature 

 unknown to Spencer and, as we saw above, wanting in 

 his scheme of evolution. Wundt adopts Kant's term 

 ' apperception,' but for him apperception is the first 

 conscious exhibition of an active principle, which he 

 identifies with the Will, and ultimately defines as the 

 special characteristic of mental life. Something analogous 

 to this principle he traces, though less and less percep- 

 tibly existing, even when we descend into the lower 

 regions of animal life. The first main characteristic of 

 this special factor is that it produces not only some- 

 thing new, but something which is continually on the 

 increase; that it is a true principle of growth and 

 development, not of mere rearrangement, of concentra- 

 tion and dissolution. There is, however, so far as I 

 know, no evidence that the insufficiency of Spencer's 

 special conception of development assisted Wundt in 

 introducing into his scheme this enlarging feature. 



The conception of this " creative synthesis," of Activity 

 as the central characteristic of mental life and develop- 

 ment, goes, with Wundt, hand in hand with the second 

 doctrine peculiar to his philosophy. This doctrine is 

 developed in his criticism of the ideas of substance and 

 causality. It distinguishes his philosophy from the older 

 ontology and metaphysics which, in modern times, have 

 found their classical expression in the system of Spinoza. 

 The conception of substance is not applicable, according 

 to Wundt, to mental phenomena, i.e., to the phenomena 

 which we know through introspection. These are purely 

 processes following each other in the sequence of time, 



