108 
to smooth over real difficulties, and to persuade where he 
cannot convince. 
In justice to Mr. Darwin, however, it must be admitted 
that the conditions of fertility and sterility are very ill under- 
stood, and that every day’s advance in knowledge leads us to 
regard the hiatus in his evidence as of less and less impor- 
tance, when set against the multitude of facts 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 philosopher 
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 embryology. 
But even leaving Mr. Darwin’s views aside, the whole 
analogy of natural operations furnishes so complete and crush- 
ing an argument against the intervention of any but what are 
termed secondary causes, in the production of all the pheno- 
mena of the universe ; that, in view of the intimate 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 organic—from blind force to con- 
scious intellect and will. 
= 
Science has fulfilled her function when she has ascertained 
