PRELIMINARY. 243 



factors. Now the size of the social aggregate is all at once 

 increased or decreased by annexation or by loss of territory ; 

 and now the average character of its units is altered by the 

 coming in of another race as conquerors or as slaves ; while, 

 as a further effect of this event, new social relations are 

 superposed on the old. In many cases the repeated over- 

 runnings of societies by one another, the minglings of peoples 

 and institutions, the breakings up and re-aggregations, so 

 destroy the continuity of normal processes as to make it 

 extremely difficult, if not impossible, to draw conclu 

 sions. 



Once more, modifications in the average mode of life 

 pursued by a society, now increasingly warlike and now 

 increasingly industrial, initiate metamorphoses : changed 

 activities generate changes of structures. Consequently there 

 have to be distinguished those progressive re-arrangements 

 caused by the further development of one social type, from 

 those caused by the commencing development of another 

 social type. The lines of an organization adapted to a mode 

 of activity which has ceased, or has been long suspended, begin 

 to fade, and are traversed by the increasingly-definite lines of 

 an organization adapted to the mode of activity which has 

 replaced it; and error may result from mistaking traits 

 belonging to the one for those belonging to the other. 



Hence we may infer that out of the complex and confused 

 evidence, only the larger truths will emerge with clearness. 

 While anticipating that certain general conclusions are to be 

 positively established, we may anticipate that more special 

 ones can be alleged only as probable. 



Happily, however, as we shall eventually see, those general 

 conclusions admitting of positive establishment, are the con 

 clusions of most value for guidance. 



