Mr. Spencer proposes to deal with feelings and functions in their mutual dependence,[9] and so admits the subjective as a factor. Thus there are feelings which are sensations and serve partly as guides and partly as stimuli towards actions for the sustenance and preservation of life. And there are feelings which are classed as emotions which also act in a very potent way as guides and stimuli, such as fear and joy. Hence, in treating of conduct under its biological aspect we are compelled to consider that inter-action of feelings and functions which is essential to animal life in all its more developed forms.[10] Following upon this we are taught that Pleasure is a feeling which we seek to bring into consciousness, and Pain a feeling which we seek to keep out of consciousness. This certainly accords to the subjective factor a commanding position in the physical action of organisms; it also implies a foresight of the results of actions, and a certain degree of advance in psychology but throws no light upon the lower stages of biological action. Mr. Spencer says, however, that "fit connections between acts and results must establish themselves in living things even before consciousness arises." This is followed by an interesting study of the proposition that "after the rise of consciousness these connections can change in no other way than to become better established," and that "whenever sentiency makes its appearance as an accompaniment, its forms must be such that in the one case the produced feeling is of a kind that will be sought--Pleasure, and in the other case is of a kind that will be shunned--Pain." "It is an inevitable deduction from the hypothesis of evolution that races of sentient creatures could have come into existence under no other conditions" than that "pains are the correlatives of actions injurious to the organism, while pleasures are the correlatives of actions conducive to its welfare."