78 ESSAYS OF A BIOLOGIST 



ology can become attached to the general body cf 

 science; and in so doing it can both receive and give. 

 Since man is but a single species of organism, and, 

 biologically speaking, a very young one; since more- 

 over he presents a peculiar type of organization, it is 

 clear that the broad principles underlying physiology 

 and evolution can best be studied on other organ- 

 isms and later applied to man. On the other hand, 

 man is the highest existing organism; thus a study 

 of the causes to which he owes his pre-eminence will 

 be important as adding to and crowning the prin- 

 ciples derived from non-human biology. Further- 

 more, not only are man's mental powers on a different 

 level from those of other animals, but psychology 

 can at present make by far its greatest contributions 

 by a study of human mind, so that the psychological 

 side of biology will for the present derive its chief 

 information from man. 



Our first affair, therefore, is to see in what im- 

 portant respects man is qualitatively unlike the rest 

 of the organic world; then to investigate what gen- 

 eral rules or principles apply equally to him and to 

 the others; and finally to see what corrections, so to 

 speak, must be made before these principles can be 

 applied to the one or to the other. 



The qualitative difference between man and other 

 organisms is a cardinal fact with orthodox biology 

 has tended to slur over or to neglect, whereas philos- 

 ophy has too often tried to magnify it unduly so as 

 to make man frankly incommensurable with his 



