444 INDUCTION. 



one by one, to ascertain whether it will combine with 

 them, or decompose them, and with what result; and 

 also apply heat, or electricity, or pressure, to discover 

 what will happen to the substance under each of these 

 circumstances. 



But if, on the other hand, it is out of our power 

 to produce the phenomenon, and we have to seek for 

 instances in which nature produces it, the task before 

 us is one of quite another kind. Instead of being 

 able to choose what the concomitant circumstances 

 shall be, we now have to discover what they are; 

 which, when we go beyond the simplest and most 

 accessible cases, it is next to impossible to do, with 

 any precision and completeness. Let us take, as an 

 exemplification of a phenomenon which we have no 

 means of fabricating artificially, a human mind. Nature 

 produces many; but the consequence of our not being 

 able to produce it by art is, that in every instance in 

 which we see a human mind developing itself, or 

 acting upon other things, we see it surrounded and 

 obscured by an indefinite multitude of unascertainable 

 circumstances, rendering the use of the common expe- 

 rimental methods almost delusive. We may conceive 

 to what extent this is true, if we consider, among other 

 things, that whenever nature produces a human mind, 

 she produces, in close connexion with it, also a body ; 

 that is, a vast complication of physical facts, in no 

 two cases perhaps exactly similar, and most of which 

 (except the mere structure, which we can examine in 

 a sort of coarse way after it has ceased to act) are 

 radically out of the reach of our means of exploration. 

 If, instead of a human mind, we suppose the subject 

 of investigation to be a human society or State, all 

 the same difficulties recur in a greatly augmented 

 degree. 



