Further, we come here to what for the purpose of our present argument is the most important consideration of all, viz. that if we could show that there were two kinds of neural or physiological processess, occurring respectively on all occasions of pleasure and pain, the fact would be valueless for proving that life must be predominantly pleasant. It is perhaps intelligible that to succeed or fail in purposive activity should bring respectively contentment and discontent rather than vice-versa; but that of two kinds of neural or physiological process, one should be accompanied by pleasure and the other by pain, is no more intelligible than if the connection were reversed. If the behaviour of any creature is affected by desires and aversions, by judgments, by feelings: if its desires and aversions or its judgments are connected with or affected by its pleasures and pains, then indeed the question with what bodily conditions its pleasures and pains are connected is part of the problem that interests the biologist—viz. what the conditions are under which the species can continue. But in that case the biologist must not claim that all the conditons of life and reproduction can be found in what happens in the body. Pleasures and pains, desires and aversions, purposes are not events that happen in the body. If they are the mere “apparence or sense” of what happens there, and alone determines survival or extinction, then what happens there to determine survival might, for all we can see, equally appear as pain or pleasure.