BIOLOGY AND SOCIOLOGY 75 



It is a very incomplete explanation of the properties 

 of water to discover that it is composed of oxygen 

 and hydrogen ; or of those of humanity to discover 

 that it is derived from lower forms of life. A pre- 

 cisely similar mistake is made by most psycho- 

 analysts, who consider that an ' explanation ' of 

 adult psychology is given by tracing in it effects of 

 the events of childhood. In all such cases it is true 

 that analysis is helped, but we are by no means 

 exempted from further study of the later (and more 

 complex) phenomena in and for themselves. Just as 

 adult psychology is qualitatively different in various 

 respects from childish psychology, so is man quali- 

 tatively different from lower organisms. Very few 

 attempts have been made to carry over conceptions 

 derived from sociology into biology. ^ But the 

 converse, as we have seen, has often been true, and 

 numerous writers — largely because purely biological 

 are simpler than human phenomena — have been 

 obsessed with the idea that the study of biology as 

 such will teach us principles which can be applied 

 directly and wholesale to human problems. 



What we have just been saying shows us the correct 

 path. Through psychology and biology, sociology 

 can become attached to the general body of science j 

 and in so doing it can both receive and give. Since 

 man is but a single species of organism, and, 



* Morley Roberts is a recent exception. See his interesting 

 book, Warfare in the Human Body. 



