70 Origin, or Process of Causation of the Series. [CHAP. in. 



will show such a result as this. The difference is much like 

 that between the tread of a thousand men who are stepping 

 without thinking of each other, and their tread when they 

 are drilled into a regiment. In the former case there is 

 the working, in one way or another, of a thousand minds; 

 in the latter, of one only. 



The investigations of this and the former chapter 

 constitute a sufficiently close examination into the detailed 

 causes by which the peculiar form of statistical results with 

 which we are concerned is actually produced, to serve the 

 purpose of a work which is occupied mainly with the methods 

 of the Science of Probability. The great importance, how 

 ever, of certain statistical or sociological enquiries will de 

 mand a recurrence in a future chapter to one particular 

 application of these statistics, viz. to those concerned with 

 some classes of human actions. 



16. The only important addition to, or modification of, 

 the foregoing remarks which I have found occasion to make 

 is due to Mr Galton. He has recently pointed out, and was 

 I believe the first to do so, that in certain cases some 

 analysis of the causal processes can be effected, and is in fact 

 absolutely necessary in order to account for the facts ob 

 served. Take, for instance, the heights of the population of 

 any country. If the distribution or dispersion of these about 

 their mean value were left to the unimpeded action of those 

 myriad productive agencies alluded to above, we should cer 

 tainly obtain such an arrangement in the posterity of any 

 one generation as had already been exhibited in the parents. 

 That is, we should find repeated in the previous stage the 

 same kind of order as we were trying to account for in the 

 following stage. 



But then, as Mr Galton insists, if such agencies acted 

 freely and independently, though we should get the same 



