166 LAY SERMONS, ADDRESSES, AND REVIEWS. [vm. 



their natural order or hierarchy, their places in this 

 hierarchy being determined by the degree of generality 

 and simplicity of the conceptions with which they 

 deal. Mathematics occupies the first, astronomy the 

 second, physics the third, chemistry the fourth, biology 

 the fifth, and sociology the sixth and last place in the 

 series. M. Comte's arguments in favour of this classi- 

 fixation are first— 



" Sa conformite esscnti^llo avec la co-ordination, on quelque sorto 

 spontanee, qui se tro-uve en effet implicitement adrnise par les savants 

 livres a l'etude dea dive] se branches de la philosophic naturelle." 



But I absolutely deny the existence of this conformity. 

 If there is one thing clear about the progress of modern 

 science, it is the tendency to reduce all scientific 

 problems, except those which are purely mathematical, 

 to questions of molecular physics — that is to say, to 

 the attractions, repulsions, motions, and co-ordination 

 of the ultimate particles of matter. Social phenomena 

 are the result of the inreraction of the components of 

 society, or men, with one another and the surrounding 

 universe. But, in the language of physical science, 

 which, by the nature of the case, is materialistic, the 

 actions of men, so far as they are recognisable by 

 science, are the results of molecular changes in the 

 ma-ter of which they are composed ; and, in the long 

 run, these must come into the hands of the physicial. 

 A fortiori, the phenomena of biology and of chemistry 

 are, in their ultimate analysis, questions of molecular 

 physics. Indeed, the fact is acknowledged by all 

 chemists and biologists who look beyond their imme- 

 diate occupations. And it is to be observed, that the 

 phenomena of biology are as directly and immediately con- 

 nected with molecular physics as are those of chemistry. 

 Molar physics, chemistry, and biology are not three 



