THE PURPOSE OF YOUTH 237 



experience seem to be stored, so to say, in some separate receptacle. 

 All physiological knowledge points to part of the grey matter on 

 the surface of the brain as the storehouse, and it is precisely this 

 region which becomes relatively larger and more complex in the 

 higher vertebrates. What we must suppose to happen in those 

 animals which possess this storehouse of experience is that when 

 stimulation occurs it calls up or awakens not only the special 

 mechanisms with which it is connected, but the reservoir of past 

 experience. The resulting action is controlled not only by the 

 mechanism, but by the effect on the mechanism of the stored expe- 

 rience. The name for this storehouse of experience is memory, 

 so that what happens in the higher animals is that response to 

 ;stimulus is increased, controlled or modified by the memory of 

 past responses. It has to be remembered that memory need not 

 be conscious. Consciousness is the most difficult idea to transfer 

 from ourselves to animals, but memory we can observe and make 

 the subject of experiment. Sometimes the word memory is applied 

 not only to the separate storing of experience in the reservoir that 

 we must believe to lie in the grey matter of the brain, but to the 

 warping of the actual mechanism. There is a distinction in fact 

 between the two. We can see the more sensitive " brain memory " 

 switched off by operation or disease, or by drugs, or by gusts of 

 passion that do not reach the mechanism. And we see by keeping 

 clear the distinction between the two the opportunity for a choice 

 of response to stimulation ; the response may be due chiefly to 

 mechanism or chiefly to memory, and if chiefly to memory, to one 

 of several memories. Add consciousness to memory, and you 

 will find it very difficult to distinguish the simultaneous know- 

 ledge of several different possible responses from what we know 

 as free will. 



These high problems have taken us far away from instinct. 

 Although what I believe to be the component parts of the instincts, 

 the responses to stimulation, can be modified by experience, the 

 more complicated and typical instincts are not modified by expe- 

 rience, and, indeed, many of them are called into play only once 

 in the life of an individual. Nature has chosen another path for 

 them. They have been built up in the long history of the race 

 into very perfect mechanisms which admit of no alteration and 

 of no blundering. Given the appropriate conditions and the result 

 follows. The animals are fully equipped to meet a certain set of 

 circumstances, and if these present themselves, the adaptation 



