204 THE FEELINGS AND EMOTIONS 
temperature, so to speak, to the boiling-point of vigorous 
action, it matters little what the psychological source of heat 
may be. If this be so, we should expect an emotional vague- 
ness, since natural selection puts no premium upon emotional 
definiteness. And from this it follows, as a corollary, that, 
whereas we may infer that an animal’s perceptual products are 
probably closely similar to our own, since sight, touch, hearing, 
smell, and taste are of value in so far as they convey definite 
meaning, in interpreting their feelings and emotions we 
have less secure grounds of inference, since all that is requisite 
is that there should be a sufficiently high emotional tempera- 
ture to afford the conditions for definite and vigorous action. 
In conclusion, then, we may say that the primary purpose 
of the evolution of feeling and emotion is to promote beneficial 
behaviour, and that the observed consonance of the psycho- 
logical end of attaining satisfaction, and the biological end of 
securing survival, seems to be due to natural selection—is, 
indeed, scarcely explicable on any other naturalistic hypothesis. 
A word of warning may be added. We have repeatedly 
spoken of biological and psychological ends. By this we mean 
what seems to the observer, as an interpreter of natural pro- 
cesses, the purpose and object of their existence. But the 
word ‘end ” is often used in such a way as to imply foresight 
and contrivance on the part of a rational being. We have 
not used it in this sense. Whether the whole of nature, in- 
cluding animal behaviour, is driven onwards to definite ends 
by an underlying Cause, is a metaphysical question. It is not 
one on which science has any right to express an opinion one 
way or the other. Science deals with the phenomena ; the 
causes of their being lie outside her province. 
