72 MENTAL EVOLUTION IN ANIMALS 



what is meant by Consciousness. For, like the word " Mind/' 

 " Consciousness " is a term which serves to convey a meaning 

 well and generally understood, but a meaning which, from 

 the peculiar nature of the case, cannot be comprehended in 

 any definition. If we say that a man or an animal is con- 

 scious, we mean that the man or animal displays the power of 

 Feeling, and if we ask what we mean by Feeling, we can only, 

 I think, answer — that which distinguishes Non-extended 

 Existence from Extended. Deeper than this we cannot go, 

 because Consciousness, being itself the basis of all thought, 

 and so of all definition, cannot be itself defined except as the 

 antithesis of its logical correlative — No-consciousness. 



Let us first regard the phenomena of Consciousness as 

 disclosed in our own or subjective experience. We shall 

 subsequently see that the elementary or undecomposable 

 units of consciousness are what we call sensations. If we 

 interrogate experience we find that an elementary state of 

 consciousness, or sensation, may exist in any degree, from 

 that of an almost unrecognizable affection, up to that of 

 unendurable pain, which monopolizes the entire field of con- 

 sciousness. More than this, from the lowest limit of per- 

 ceptible sensation there arises a long and indefinite descent 

 through sensation that is not perceptible, or through sensation 

 that is sub-conscious, before we arrive at nervous action 

 which we feel entitled to regard as unconscious. This is 

 proved by those grades of almost unconscious action, passing 

 at last into wholly unconscious action, which we all know as 

 frequently occurring in the descent, through repetition or 

 habit, of consciously intelligent adjustments to automatic 

 adjustments, or adjustments performed unconsciously. Thus 

 it is evident, not only that consciousness admits of numberless 

 degrees of intensity, but that in its lower degrees its ascent 

 from no-consciousness is so gradual, that even within the 

 range of our own subjective experience we find it impossible 

 to determine within wide limits where consciousness first 

 emerges.* 



With this gradual dawn of consciousness as revealed to 

 subjective analysis, we should expect some facts of physiology, 

 or of objective analysis, to correspond; and this we do find. 



* Any one who has gradually fainted, or has slowly been put under the 

 influence of an anaesthetic, will remember the peculiar experience of feeling 

 consciousness becoming obliterated by stages 



