GENERATION OF ANIMALS, II. vi. 



bone is still soft in the case of children. The reason 

 why this occurs especially in man is that in man 

 the brain is more fluid and greater in volume than 

 in any other animal, and the reason of this, in its 

 turn, is that the heat in the heart is purest in man. 

 The fineness of the blend " in man is shown by his 

 possession of intellect : there is no other animal which 

 is so intelligent. Even children however for a con- 

 siderable period lack full control over their heads. 

 This is due to the weight of the brain, and the same 

 may be said of those parts of the body which have to 

 be moved. It is quite late before the principle of 

 movement gets control over the upper parts ; and 

 its control over those parts (such as the legs) whose 

 movement is not closely connected with it is achieved 

 last of all. Another such part is the eyeUd. Now, as 

 Nature does nothing that is superfluous or pointless, 

 it is plain that she will not do anything too late or too 

 soon, for in that case what was done would be either 

 pointless or superfluous. Therefore the separation 

 of the eyelids and the ability to move them must 

 coincide in time. Thus the completion of the forma- 

 tion of the eyes comes late, because of the large 

 amount of concoction required by the brain, and it 

 comes last, after all the other parts, because the 

 movement * must be very strong and powerful in 

 order to move parts which are so far away from the 

 first principle,*' and so much subjected to cold. That 

 such is the nature of the eyelids is shown by the 

 fact that even if a very little heaviness affects the 

 head through sleep or intoxication or anything of 

 that sort, we are unable to raise the eyeUds although 

 their weight is very sUght. 



' Viz., of movement, i.e., the heart. 



229 



