PEEFACE 



THIS treatise, compiled in connection with a scheme 

 for research work in general sociology, elaborated 

 in June 1894, was presented to the Institute of 

 Sociology at Brussels. In drawing up the pro- 

 gramme of the Institute, the founder, M. Ernest 

 Solvay, after having mentioned the questions which 

 especially called for the investigation of his col- 

 leagues, added the following statement : 



" The Institute of Sociology will take part in the 

 labours of the modern school of Sociology, the object 

 of which is to ascertain the normal conditions under 

 which societies exist, and the laws which govern their 

 evolution. But the advances of Natural Science in 

 this century have not yet been sufficiently assimilated 

 by those Sciences most closely related to it, and it 

 is from such assimilation that the most important 

 additions to knowledge may be expected." 



In stating that the results of Natural Science 

 have not been sufficiently assimilated by Sociology, 

 M. Solvay is only apparently at variance with 

 those who rightly protest against exaggerated and 



