518 INDUCTION. 



of the separate weights of the two ingredients. If 

 there had not been this exception to the entire disap- 

 pearance, in the compound, of the laws of the separate 

 ingredients ; if the combined agents had not, in this 

 one particular of weight, preserved their own laws, 

 and produced a joint result equal to the sum of their 

 separate results ; we should never, probably, have had 

 the notion now implied by the words chemical com- 

 position : and, in the fact of water produced from 

 hydrogen and oxygen and hydrogen and oxygen pro- 

 duced from water, as the transformation would have 

 been complete, we should have seen only a trans- 

 formation. 



In these cases, then, when the heteropathic effect 

 (as we called it in a former chapter) is but a trans- 

 formation of its cause, or in other words, when the 

 effect and its cause are reciprocally such, and mutu- 

 ally convertible into each other; the problem of 

 finding the cause resolves itself into the far easier one 

 of finding an effect, which is the kind of inquiry that 

 admits of being prosecuted by direct experiment. But 

 there are other cases of heteropathic effects to which 

 this mode of investigation is not applicable. Take, for 

 instance, the heteropathic laws of mind; that portion 

 of the phenomena of our mental nature which are 

 analogous to chemical rather than to dynamical phe- 

 nomena ; as when a complex passion is formed by the 

 coalition of several elementary impulses, or a complex 

 emotion by several simple pleasures or pains, of which 

 it is the result, without being the aggregate, or in any 

 respect homogeneous with them. The product, in 

 these cases, is generated by its various factors ; but 

 the factors cannot be re -produced from the product : 

 just as a youth can grow into an old man, but an old 

 man cannot grow into a youth. We cannot ascertain 



