76 ESSAYS OF A BIOLOGIST 



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 organisms 

 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 principles 

 derived from non-human biology. Furthermore, 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 informa- 

 tion from man. 



Our first affair, therefore, is to see in what important 

 respects man is qualitatively unl i k e the rest of the 

 organic world ; then to investigate what general 

 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 which orthodox biology 

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

 sophy has too often tried to magnify it unduly so as 

 to make man frankly incommensurable with his 

 lower relatives, a creature not only unique but 

 disparate. 



