THE WONDER OF LIFE 645 



others in maintaining that Biology must be ranked beside 

 Physics as a fundamental and autonomous science. An- 

 other line of argument would, we beheve, lead us, even 

 from the naturahst's point of view, to recognize the auto- 

 nomy of Psychology. 



We recognize, then, three orders of facts : the physical 

 order, where mechanism reigns, where mechanical formulae 

 suffice for the description of what goes on ; the animate 

 order, where mechanism is transcended ; and the psychical 

 order, where mechanism is irrelevant. It is plain that the 

 physical order overlaps the animate order, for organisms 

 are material systems, and their hfe includes a concatena- 

 tion of chemico-physical processes. At the same time, as 

 we have seen, we cannot explain the fundamental pro- 

 perties of the organism, which we start with in biology, in 

 chemico-physical terms, nor would a complete chemico- 

 physical description of what goes on in the hfe of the 

 organism be the kind of description which a biologist seeks. 

 The ^me apphes to the psychical order, which is overlapped 

 by the biological. In short, the sciences are differentiated 

 not only by their subject matter, but by their characteristic 

 questions and methods and concepts. 



Perhaps we may be allowed to refer to three remarks 

 which are often made in regard to this sort of discussion 

 by the plain man in the street, from whom most of us, after 

 all, are not far removed. He is surprised, in the first 

 place, at the longevity of the problem of vitalism and the 

 oscillations of human judgment from one side to another. 

 An old question indeed, for Aristotle was a thorough-going 

 vitahst, and his biology was in conscious opposition to the 

 school of Democritus. And from that time we have had 

 periodic oscillations between vitaUstic and mechanistic 



