500 PROGRESS OF SCIENCE IN THE CENTURY. 



transforms human nature and social institutions ; and 

 this fact affords the true interpretation of all social 

 progress." 



" Such, in its chief theoretical conceptions, is the 

 great sociological system put forth by a master mind, 

 to which all other modern systems of sociological 

 thought, and all more special sociological studies, in 

 one or another way are related." * 



(3) As it seems to us, a third historical step of the 

 greatest moment is marked by the work of 



" Frederic Le Play, an economist whose name is 

 strange to most people, even to most Frenchmen, but 

 whose thought has none the less been in many ways 

 widely and popularly active throughout the century, 

 and has been and is even now silently working in many 

 channels, at first mainly practical, but now also theo- 

 retic and speculative. There are social workers and 

 social students who would estimate his influence on 

 action and his impulse towards thought as alike quite 

 among the very greatest in actual value and in probable 

 usefulness which the nineteenth century is handing 

 towards the twentieth, and this with no disrespect to or 

 forgetfulness of its many great and better-known per- 

 sonalities and forces." t 



Le Play turned a fertile brain and a remarkable 

 organising genius to the problem of the concrete in- 

 terpretation of existing social groups in terms of 

 the three biological categories, Environment, Func- 

 tion, and Kinship, or, as he phrased it, "Lieu, 

 Travail, Famille" We shall return to this three- 

 fold interpretation in a subsequent section. 



* Modern Sociology, Internal . Monthly, Nov., 1900, p. 543. 

 See also his Principles of Sociology. 



f Prof. Patrick Geddes, Man and the Environment, Intemat. 

 Monthly, 1. (1900), p. 179. 



