412 FRAGMENTS OF SCIENCE 



reached its very rim, a mighty Mystery still looms beyond 

 us. We have, in fact, made no step toward its solution. 

 And thus it will ever loom, compelling the philosophies 

 of successive ages to confess that 



•* 'We are such stuff 

 As dreams are made of, and our little life 

 la rounded by a sleep.' ** 



In my work on *'Heat,** published in 1863, and repub- 

 lished many times since, I employ the precise language 

 thus extracted from the ** Saturday Review." 



The distinction is here clearly brought out which I 

 had resolved at all hazards to draw — that, namely, be- 

 tween what men knew or might know, and what they 

 could never hope to know. Impart simple magnifying 

 power to our present vision, and the atomic motions of 

 the brain itself might be brought into view. Compare 

 these motions with the corresponding states of conscious- 

 ness, and an empirical nexus might be established; but 

 "we try to soar in a vacuum when we endeavor to pass 

 by logical deduction from the one to the other. ' ' Among 

 these brain-effects a new product appears which defies 

 mechanical treatment. We cannot deduce motion from 

 consciousness or consciousness from motion as we deduce 

 one motion from another. Nevertheless observation is 

 open to us, and by it relations may be established which 

 are at least as valid as those of the deductive reason. The 

 difficulty may really lie in the attempt to convert a datum 

 into an inference — an ultimate fact into a product of logic. 

 My desire for the moment, however, is not to theorize, 

 but to let facts speak in reply to accusation. 



The most "materialistic" speculation for which I was 



