ZOOLOGY, AND THE PHILOSOPHY OF EVOLUTION 137 



things, we cannot believe that life and consciousness and reason 

 and volition are anything but part of nature. The question the 

 zoologist would like to answer is, what their place in nature is. 

 So far as I am aware, no one believes that these aspects of nature 

 exist in themselves, without antecedents, for we know that many 

 of their antecedents are physical, and we want to find out, if we 

 can, whether this is true of all of them or not. For my own part, 

 I fail to see what bearing this wish has on the question whether 

 the order of nature is " fixed " or unfixed ; nor can I see how 

 proof that the conditions which, being given, are good reasons 

 for expecting reason or the moral sense, are mechanical, should 

 show that reason and morality are useless. 



They who take refuge in an imponderable ether as soon as 

 they find it difficult to discover, in ponderable matter, the key to 

 all the antecedents to certain phenomena of light and electricity, 

 have no reason to cry out that the fixed order of nature is threat- 

 ened, because the modest zoologist has not yet been able to find, 

 in ponderable matter and physical energy, the key to all his 

 problems. 



Berkeley tells us that human knowledge has its basis in experi- 

 ence, and that its scientific value is to be measured by the amount 

 of this experience; and Huxley assures us that there is but one 

 kind of knowledge and but one way to acquire it. They hold our 

 practical test of truth to be evidence, although a pious evolutionist, 

 who admits that, for all he knows, they may be right, is a heretic ; 

 for Herbert Spencer tells him that the Philosophy of Evolution 

 stands or falls with the assertion that the ultimate criterion of truth 

 is inability to conceive its negative. 



If you will read Part VII. of his " Principles of Psychology" with 

 care, you will note that its author ' tells us that, unless we admit 

 this, we cannot be his disciples. It is not enough to admit igno- 

 rance of things ultimate, or to confess that, for all one knows, in- 

 ability to conceive its negative may sometime prove to be the 

 ultimate criterion of truth. One may admit that he is unable to 

 discover any line which separates the responsive actions of living 

 things in general from the rational actions of thinking men ; that 

 he does not know how or where instinct and impulse and emotion 

 give place to reason. One may have as little faith in the idealism of 



