ii.] DEVELOPMENT OF ANIMAL LIFE 135 



Vegetative torpor, instinct, and intelligence — these, 

 then, are the elements that coincided in the vital impulsion 

 common to plants and animals, and which, in the course 

 of a development in which they were made manifest in 

 the most unforeseen forms, have been dissociated by the 

 very fact of their growth. The cardinal error which, from 

 Aristotle onwards, has vitiated most of the philosophies of 

 nature, is to see in vegetative, instinctive and rational life, 

 three successive degrees of the development of one and the 

 same tendency, whereas they are three divergent directions 

 of an activity that has split up as it grew. The difference 

 between them is not a difference of intensity, nor, more 

 generally, of degree, but of kind. 



It is important to investigate this point. We have 

 seen in the case of vegetable and animal life how they 

 are at once mutually complementary and mutually an- 

 tagonistic. Now we must show that intelligence and 

 instinct also are opposite and complementary. But 

 let us first explain why we are generally led to regard 

 them as activities of which one is superior to the other 

 and based upon it, whereas in reality they are not things 

 of the same order: they have not succeeded one another, 

 nor can we assign to them different grades. 



It is because intelligence and instinct, having origin- 

 ally been interpenetrating, retain something of their 

 common origin. Neither is ever found in a pure state. 

 We said that in the plant the consciousness and mobility 

 of the animal, which lie dormant, can be awakened; and 

 that the animal lives under the constant menace of being 

 drawn aside to the vegetative life. The two tendencies 

 — that of the plant and that of the animal — were so thor- 

 oughly interpenetrating, to begin with, that there has 

 never been a complete severance between them: they 



