256 INDUCTION. 



Where tvvo plienomena, between the laws or properties of which 

 considered in themselves no connexion can be traced, are thus recipro- 

 cally cause and effect, each capable in its turn of being produced from 

 the other, and each, when it produces the other, ceasing itself to exist 

 (■as water is produced fi-ora oxygen and hydrogen, and oxygen and 

 hydrogen are reproduced from water); this causation of the two 

 pbenonlena by one another, each of them being generated by the 

 .other's destruction, is properly ti-ansfonnation. The idea of chemical 

 composition is an idea of transfomiation, but of a transfonnation which 

 is incomplete ; since we consider the oxygen and hydrogen to be 

 present in the water as oxygen and hydrogen, and- capable of, being 

 discx)vered in it if our senses were sufficiently keen : a supposition (for 

 it is no more) grounded solely upon the fact, that the weight of the 

 water is the sum of the separate weights of the two ingredients. If 

 there had not been this exception to the entire disappearance, 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 composition : and, in the fact of water produced 

 fi-om hydrogen and oxygen and hydrogen and oxygen produced from 

 water, as the transformation would have been complete, we should 

 have seen only a transformation. • 



In these cases, then, when the heteropathic effect (as we called it in 

 a former chapter) is but a transformation of its cause, or in other 

 words, when the effect and its cause are reciprocally such, and 

 mutually 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 ajiplicable. 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 phenomena; 

 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 reproduced 

 from the product : just as a youth can gi'ow into an old man, but an 

 old man cannot grow into a youth. We cannot ascertain from what 

 simple feelings any of our complex states of mind are ^eiierated, as 

 we ascertain the ingredients of a chemical compound, by making it, 

 in its turn, generate them. We can only, therefore, discover these 

 laws by the slow process of studying the simple feelings themselves, 

 and ascertaining synthetically, by experimenting on the various com- 

 binations of which they are susceptible, what they, by their mutual 

 action upon one another, are capable of generating. 



§ 5. It might have been supposed that the other, and apparently 

 simpler variety of the mutual interference of causes, where each cause 

 continues to produce its own proper effect according to the same laws 

 to which it confonns in its separate state, would have presented fewer 

 difficulties to the inductive inquirer than that of which we have just 



