ii.] INTELLIGENCE AND INSTINCT 143 



is attested by the very insufficiency of the natural means 

 at man's disposal for defense against his enemies, against 

 cold and hunger. This insufficiency, when we strive to 

 fathom its significance, acquires the value of a prehistoric 

 document; it is the final leave-taking between intelli- 

 gence and instinct. But it is no less true that nature 

 must have hesitated between two modes of psychical 

 activity — one assured of immediate success, but limited 

 in its effects; the other hazardous, but whose conquests, 

 if it should reach independence, might be extended in- 

 definitely. Here again, then, the greatest success was 

 achieved on the side of the greatest risk. Instinct and 

 intelligence therefore represent two divergent solutions, 

 equally fitting, of one and the same problem. 



There ensue, it is true, profound differences of internal 

 structure between instinct and intelligence. We shall 

 dwell only on those that concern our present study. Let 

 us say, then, that instinct and intelligence imply two 

 radically different kinds of knowledge. But some ex- 

 planations are first of all necessary on the subject of con- 

 sciousness in general. 



It has been asked how far instinct is conscious. Our 

 reply is that there are a vast number of differences and 

 degrees, that instinct is more or less conscious in certain 

 cases, unconscious in others. The plant, as we shall see, 

 has instincts; it is not likely that these are accompanied 

 by feeling. Even in the animal there is hai ly any com- 

 plex instinct that is not unconscious in some part at least 

 of its exercise. But here we must point out a difference, 

 not often noticed, between two kinds of unconsciousness, 

 viz., that in which consciousness is absent, and that in which 

 consciousness is nullified. Both are equal to zero, but in 

 one case the zero expresses the fact that there is nothing, 

 in the other that we have two equal quantities of opposite 



