SECT. 4.] Origin, or Process of Causation of the Series. 57 



[ as to destroy all the uniformity of its effects. Practically 

 j neither is the case. The second condition simply varies the 

 details, leaving the uniformity on the whole of precisely 

 the same general description as it was before. Or if the 

 objects were supposed to be absolutely alike, as in the case 

 of successive throws of a penny, it may serve to bring about 

 a uniformity. Analysis will show these agencies to be 

 thus made up of an almost infinite number of different 

 components, but it will detect the same peculiarity that 

 we have so often had occasion to refer to, pervading almost 

 all these components. The proportions in which they are 

 combined will be found to be nearly, though not quite, the 

 same; the intensity with which they act will be nearly 

 though not quite equal. And they will all unite and blend 

 into a more and more perfect regularity as we proceed to 

 take the average of a larger number of instances. 



Take, for instance, the length of life. As we have seen, 

 the constitutions of a very large number of persons selected 

 at random will be found to present much the same feature ; 

 general uniformity accompanied by individual irregularity. 

 Now when these persons go out into the world, they are 

 exposed to a variety of agencies, the collective influence 

 of which will assign to each the length of life allotted to 

 him. These agencies are of course innumerable, and their 

 mutual interaction complicated beyond all power of analysis 

 to extricate. Each effect becomes in its turn a cause, is 

 interwoven inextricably with an indefinite number of other 

 causes, and reacts upon the final result. Climate, food, 

 clothing, are some of these agencies, or rather comprise 

 aggregate groups of them. The nature of a man s work 

 is also important. One man overworks himself, another 

 follows an unhealthy trade, a third exposes himself to in 

 fection, and so on. 



