THE TWO ASPECTS OF SCIENCE 13 



briefly one other matter which belongs properly to this 

 preliminary stage. Are we right to speak at all of 

 " science " ? Every one knows to-day that there is not 

 one science but many. Physics, chemistry, astronomy, 

 geology, zoology, botany, physiology, psychology, and so 

 on, although all called " sciences," seem to be branches 

 of knowledge almost as separate as any science is from 

 philosophy. A chemist may be as ignorant of botany 

 as a philosopher of mathematics. Can we say anything 

 that is true of all these sciences and is not equally true 

 of mathematics or philosophy ? Well, that is one of the 

 questions that we have to answer, and our answer will 

 be affirmative ; we shall lay down a criterion which 

 appears to distinguish all sciences from any other branch 



ure learning. But a word may be said here about 

 the relations of the different sciences. 



The division between them corresponds in part to the 

 crude common-sense division of the external world of 

 nature. Thus we find some sciences (zoology, botany, 



iology) dealing with living beings and others (physics 

 and chemistry) with inanimate " matter." Further we 

 can distinguish sciences which deal with particular 

 objects from those which deal with the common sub- 

 stratum of objects. Thus geology deals with one parti- 

 cular object, the earth ; and astronomy with other 

 particular objects, the stars ; zoology and botany 



ider particular animal- and plants. On the other 

 hand physics and chemistry deal with the substai 

 . iiich all particular material objects are composed; 



iology with the functions common to all living 



beings. So f,n ih< divi-inn- 1, < nces lie 



tin- liiK that \\v should expect if science is the 



world of nature. But such divi-ion^ c.m 



t>e made very roughly. The pro vine < ; a 1 1 y 



regarded to-day as belonging to each sci< very 



largely t: It of historical accid< nt ; one line of 



