56 A Century of Science 



brain secretes thought as the liver secretes bile. 

 If he were alive to-day, he would doubtless smile 

 at this old form of expression as crude, and would 

 adopt a more subtle phrase; he would say that 

 " thought is transformed motion." 



Against this interpretation I have maintained 

 that the theory of correlation not only fails to sup- 

 port it, but actually overthrows it. The arguments 

 may be found in the chapter on Matter and Spirit, 

 in my " Cosmic Philosophy," published in 1874, and 

 in the essay entitled " A Crumb for the Modern 

 Symposium," written in 1877, and reprinted in 

 " Darwinism and Other Essays." l Their purport is, 

 that in tracing the correlation of motions into the or- 

 ganism through the nervous system and out again, 

 we are bound to get an account of each step in 

 terms of motion. Unless we can show that every 

 unit of motion that disappears is transformed into 

 an exact quantitative equivalent, our theory of cor- 

 relation breaks down ; but when we have shown this 

 we shall have given a complete account of the 

 whole affair without taking any heed whatever of 

 thought, feeling, or consciousness. In other words, 

 these psychical activities do not enter into the cir- 

 cuit, but stand outside of it, as a segment of a 

 circle may stand outside a portion of an entire cir- 



1 See also Excursions of an Evolutionist, 1883, pp. 274-282. 



