128 THE RELATIONS OF MAN 



which harmonize with, or receive an explanation from, his 

 doctrines. 



I adopt Mr. Darwin's hypothesis, therefore, subject to 

 the production of proof that physiological species may be 

 produced by selective breeding ; just as a physical philoso- 

 pher may accept the undulatory theory of light, subject 

 to. the proof of the existence of the hypothetical ether ; or 

 as the chemist adopts the atomic theory, subject to the 

 proof of the existence of atoms ; and for exactly the same 

 reasons, namely, that it has an immense amount of prima 

 facie probability : that it is the only means at present 

 within reach of reducing the chaos of observed facts to 

 order ; and lastly, that it is the most powerful instrument 

 of investigation which has been presented to naturalists 

 since the invention of the natural system of classification 

 and the commencement of the systematic study of embry- 

 ology. 



But even leaving Mr. Darwin's views aside, the whole 

 analogy of natural operations furnishes so complete and 

 crushing an argument against the intervention of any but 

 what are termed secondary causes, in the production of all 

 the phenomena of the universe ; that, in view of the inti- 

 mate relations between Man and the rest of the living 

 world ; and between the forces exerted by the latter and 

 all other forces, I can see no excuse for doubting that all 

 are co-ordinated terms of Nature's great progression, from 

 the formless to the formed — from the inorganic to the or- 

 ganic — from blind force to conscious intellect and will. 



Science has fulfilled her function when she has ascer- 

 tained and enunciated truth ; and were these pages ad- 

 dressed to men of science only, I should now close this 

 essay, knowing that my colleagues have learned to respect 

 nothing but evidence, and to believe that their highest 



