An Introduction to a Biology 



lay aside liis implement when he has done with it and 

 pick it up when he wants to use it again. And 

 this involves at the moment when he lays it down 

 a looking forward to the time when he will want 

 it again ; and, at the moment when he wants it 

 again, a looking back to — that is, a memory of — the 

 time when he laid it down. Here we get our first 

 glimpse of the essential feature which distinguishes 

 the mind of man from that of other animals — namely, 

 the fact that the human mind extends its operation 

 much further forwards and much further backwards 

 than does that of the other animals. 



§2 



This essential identity between the tool (or limb) 

 which is part of the body and the tool which is de- 

 tachable from it is a very important point to grasp, 

 because it forms the starting point of our study 

 of evolution in man. 



I am aware that this thesis conflicts with what 

 may be called a sensible scientific view of the matter. 

 According to that view the claw of the crab corre- 

 sponds with the hand of the man ; the tips of a 

 crab's claws correspond with the tips of a man's 

 fingers, and not to the points of his forceps whilst 

 he is holding them. But this scientific view surely 

 does not express the whole truth. To know the 

 real living thing we must see it in relation to its 

 surroundings and know how it obtains its food, 

 and how it escapes from or defeats its enemies. 

 A specimen of a crab in a bottle shows you the 

 crab accoutred with the full panoply of armour and 



weapons which protect him from his enemies and 



46 



