GREEK BIOLOGY AND MEDICINE 



reproduction of their own particular species, 

 and the sphere of action with certain animals 

 is similarly limited. The faculty of reproduc- 

 tion, then, is common to all alike. If sensibility 

 be superadded, then their lives will differ from 

 one another in respect to sexual intercourse 

 through the varying amount of pleasure de- 

 rived therefrom, and also in regard to modes 

 of parturition and the ways of rearing their 

 young. Some animals, like plants, simply 

 procreate their own species at different seasons ; 

 other animals busy themselves also in pro- 

 curing food for their young, and after they are 

 reared quit them and have no further dealings 

 with them; other animals are more intelligent 

 and endowed with memory, and they live with 

 their offspring for a longer period and on a more 

 social footing. 



"The life of animals, then, may be divided 

 into two acts, — procreation and feeding; for 

 on these two acts all their interests and life 

 concentrate. Their food depends chiefly on 

 the substance of which they are severally con- 

 stituted; for the source of their growth in all 

 cases will be this substance. And whatever 

 is in conformity with nature is pleasant, and 

 all animals pursue pleasure in keeping with 

 their nature." 31 



[52] 



