March 28, 1902.] 



SCIENCE. 



491 



the cells which arise from the egg is some- 

 times inherent in the egg, and sometimes 

 induced by the conditions of development, 

 it is more commonly mixed ; but may it not 

 be the mind of the embryologist, and not 

 the natural world, that is mixed? Science 

 does not deal in compromises, but in dis- 

 coveries. When we say the development 

 of the egg is inherent, must we not also 

 say what are the relations with reference 

 to which it is inherent? When we say it 

 is induced, must we not also say what are 

 the relations with reference to which it is 

 induced? Is there any way to find this 

 out except scientific discovery? 



19. J.re the beneficial effects of practice 

 and training and education and opportu- 

 nity innate or superadded? 



Can we hope to answer this question, a 

 priori, by deduction from hypotheses? Is 

 there any more value in Weismann's 

 demonstration that acquired characters 

 cannot be inherited than there is in 

 Haeckel's declaration that the inheritance 

 of acquired charactei's is a necessary axiom 

 of the monistic creed? 



Such facts as are in my possession seem 

 to me to show that, while we need oppor- 

 tunities to make the best of our natviral 

 abilities, no one can do his part in any 

 station in life without natural aptitude. 

 As my opinion is not a deduction from a 

 hypothesis, I hold it lightly, and subject to 

 revision and correction. 



20. May not the biological notion of a 

 living substance be an illustration of the 

 fallacy of the imdistributed middle? 



AVhen we say all living things are alike 

 in substance, I cannot discover that we 

 mean anything more than we mean when, 

 admitting some report of a conversation 

 as a substitute for the truth for some pur- 

 pose that we have in view, we say it is the 

 same in substance as the original conversa- 

 tion. 



The modern naturalist is so well aware 



of the endless diversity of living things 

 that he never — that is, hardly ever — 

 thinks that because one amoeba, or one 

 yeast-plant, or one horse, will serve certain 

 purposes of experiment, and demonstra- 

 tion, and instruction, as well as another, 

 they are alike in any respect whatever. 



21. Conclusion. 



As my only purpose is to do what I can 

 to make the way clear for the progress of 

 embryologieal science, by trying- to free 

 my own mind, and the minds of others, 

 from all notions which imply that embry- 

 ologieal science is impossible, and not to 

 give a natural history of mind, I have 

 passed by many important aspects of 

 human knowledge without notice. But, 

 before I close, I ask you to take away with 

 you, and to consider, this familiar fact: 

 Philosophers tell us we may come at truth 

 by deducing it from certain first prin- 

 ciples which are self-evident to the normal 

 man, and they talk about the normal man 

 as if he were a prominent citizen, the 

 familiar acquaintance of all who have any 

 claim to be considered men of intellect, 

 and a well-known face even to the com- 

 mon herd. The naturalist declares he 

 knows no such person, that all men are 

 individual and particular men, and the 

 normal man a fictitioiis character, and a' 

 statistical average without opinions. 



If the naturalist is honest with himself, 

 it seems to me that he cannot fail to come 

 in time to hold his most cherished convic- 

 tions subject to revision, and to value them 

 only when they are verified by laying them 

 alongside nature, and to regard absolute 

 truth and necessary truth as meaningless 

 words, because the being of things is not 

 absolute but relative to everything else in 

 nature. 



The truth that l^nowledge is not abso- 

 lute, but relative, is held to be the final 

 and conclusive proof that we can never 

 know anything as it really is, for we are 



