xii ACTIVITY AND SUBSTANCE 223 



becomes either a needless nullity or an unknowable, an 

 inscrutable substratum which is conceived to underlie 

 everything, but explains nothing, just because it is un 

 knowable and can neither be experienced nor examined. 

 In this form, therefore, the conception of Substance has 

 no value for any purpose whatsoever, either philosophic 

 or scientific. 



But philosophers have been slow to find this out, 

 though it is a melancholy satisfaction that, even so, they 

 have anticipated the scientists. Berkeley, arguing from 

 the current notion of Substance, had the genius to per 

 ceive that material substance was a philosophic super 

 fluity. Hume promptly extended this argument to the 

 destruction of spiritual substance. He pointed out that 

 apart from its states there was no self or soul. So he 

 resolved the self into the sequence of its states of con 

 sciousness. 1 



Both Berkeley and Hume were fully justified in their 

 criticism. How right they were the sciences proceeded 

 to discover on their own account. In the last thirty years 

 it has become quite a commonplace in psychology to 

 proclaim soul-substance useless, and to conceive the 

 mind as consisting of a stream of consciousness. And 

 at the present moment physicists seem to be finally 

 making up their minds that the matter which had 

 lingered on in physics as the substrate of physical pheno 

 mena is mere scaffolding, and that all scientific facts 

 can really be more simply and conveniently conceived as 

 transformations of energy. Now it would not yet be 

 true to say that the conception of Energy in modern 

 science coincides with the ancient conception of Energeia. 

 But they agree in rejecting the old notion of substance 

 as a substratum. It is clear, moreover, that they are 

 akin in spirit, and that in the hands of a master like 

 Prof. Ostwald 2 the conception of energy is rapidly 



1 J. S. Mill similarly sees that Substance is only postulated as a support for 

 phenomena, and that if we think away the support and suppose the phenomena 

 to remain without any agency but an internal law, every consequence, for the sake 

 of which Substance was assumed, will follow without Substance. Exam, of 

 Hamilton, p. 252. 



2 See his admirable treatise on Naturphilosophie. 



