50 Arrangement and Formation of the Series. [CHAP. n. 



respond to certain limits of excellency or deficiency. 1 All 

 that is necessary for such a purpose is that the rate of 1 

 departure from the mean should be tolerably constant under 

 widely different circumstances : in this case throughout all 

 the races of man. Of course if the law of divergence is 

 the same as that which prevails in inanimate nature we 

 have a still wider and more natural system of classification 

 at hand, and one which ought to be familiar, more or less, to 

 every one who has thus to estimate qualities. 



21. Perhaps one of the best illustrations of the legi 

 timate application of such principles is to be found in Mr 

 Galton s work on Hereditary Genius. Indeed the full force 

 and purport of some of his reasonings there can hardly be] 

 appreciated except by those who are familiar with the con 

 ceptions which we have been discussing in this chapter. We 

 can only afford space to notice one or two points, but the| 

 student will find in the perusal, of at any rate the more 

 argumentive parts, of that volume 2 an interesting illustration 

 of the doctrines now under discussion. For one thing it 

 may be safely asserted, that no one unfamiliar with the Law 

 of Error would ever in the least appreciate the excessive 



1 Perhaps the best hrief account with some approach to accuracy, 



of Mr Galton s method is to be found select the middlemost person in the 



in a paper in Mind (July, 1880) on row and use him as a basis of com- 



the statistics of Mental Imagery. parison with the corresponding per- 



The subject under comparison here son in any other batch. And simi- 



viz. the relative power, possessed larly with those who occupy other 



by different persons, of raising clear relative positions than that of the 



visual images of objects no longer middlemost, 



present to us is one which it seems 2 j refer to tlie introductory and 



impossible to measure , in the ordi- concluding chapters: the bulk of the 



nary sense of the term. But by book is, from the nature of the case, 



arranging all the answers in the mainly occupied with statistical and 



order in which the faculty in ques- biographical details, 

 tion seems to be possessed we can, 



