IDIOSYNCRASY. 389 



Why, with a thousand red and a thousand white balls, shaken togeth- 

 er with an equal energy by a machine (if you will), and poured out 

 on our billiard-table, should there be a similar diversity ? The fact 

 is, you can not get absolute identity of conditions in any two cases. 

 Imagine yourself mixing two fluids together with a spoon, as regularly 

 as you choose ; can you possibly make the currents in the two exactly 

 alike twice running ? And here in the case of humanity you have not 

 to deal with simple red beans or with simple fluids, but with very com- 

 plex gemmules or very complex physiological units. 



If even in twins we can not expect perfect similarity, still less can 

 we expect it in mere ordinary brothers and sisters. Here, innumerable 

 minor physiological conditions of either parent may affect the result 

 in infinite ways. Not, indeed, that there is any sufficient reason for 

 supposing passing states of health and so forth directly to impress 

 themselves upon the heredity of the offspring ; but one can readily 

 understand that, in a process which is essentially a mixture of ele- 

 ments, small varieties of external circumstances may vastly alter the 

 nature of the result. Shake the bag of beans once, and you get one 

 arrangement ; shake it once more, and you get another and very dif- 

 ferent one. To this extent, and to this extent only, as it seems to me, 

 chance in the true sense enters into the composition of an individual- 

 ity. The possible elements which may go to make up the mental con- 

 stitution of any person are (as I shall try to show) strictly limited to 

 all those elements, actual or latent, which exist in the two persons of 

 his parents ; but the particular mixture of those elements which will 

 come out in him the number to be selected and the number to be 

 rejected out of all the possible combinations will depend upon that 

 minute interaction of small physical causes, working unseen, which we 

 properly designate by the convenient name of chance. In this sense, 

 it is not a chance that William Jones, the son of two English parents, 

 is born an Englishman in physique and mental peculiarities, rather 

 than a Chinese or a negro ; nor is it a chance that he is born essentially 

 a compound of his ancestors on the Jones side and on the Brown side, 

 but it is a chance that he is born a boy rather than a girl ; and it is 

 a chance that he is born himself rather than his brother John or his 

 brother Thomas. If we knew all, we could point out exactly why this 

 result and not any other result occurred just there and then ; but, as 

 we do not know all, we fairly say that the result is in so far a chance 

 one. And, even if we knew all, we should still be justified in using 

 the same language, for it marks a real difference in causation. Will- 

 iam Jones is an Englishman and a Jones-Brown strictly in virtue of 

 his being the son of Henry Jones and Mary Brown ; but so are all his 

 brothers and (mutatis mutandis) his sisters too. He is himself, and 

 not one of hi3 brothers or his sisters, in virtue of certain minute mo- 

 lecular arrangements, occurring between certain elements for the most 

 part essentially identical with the elements which went to make up 



