INTERMIXTUKE OF EFFECTS. 317 



probably, have had the notion now implied by the words chemical compo- 

 sition ; and, in the facts of water produced from hydrogen and oxygen, 

 and liydrogen and oxygen produced from watei', as the transformation 

 would have been complete, we should have seen only a transformation. 



In these cases, Avhere the heteropathic effect (as we called it in a former 

 chapter)* is but a transformation of its cause, or in other words, where 

 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 applicable. 

 Take, for instance, the heteropathic laws of mind ; that portion of the phe- 

 nomena of our mental nature which are analogous to chemical rather than 

 to dynamical phenomena ; as when a complex passion is formed by the co- 

 alition of several elementary impulses, or a complex emotion by several 

 simple pleasures or pains, of which it is the result without being the ag- 

 gregate, or in any respect homogeneous with them. The product, in these 

 cases, is generated by its various factors ; but the factors can not be re- 

 produced from the product; just as a youth can grow into an old man, 

 but an old man can not grow into a youth. We can not ascertain from 

 what simple feelings any of our complex states of mind are generated, 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 combinations 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 

 conforms in its separate state, would have presented fewer difficulties to 

 the inductive inquirer than that of which we have just finished the consid- 

 eration. It presents, however, so far as direct induction apart from de- 

 duction is concerned, infinitely greater difficulties. When a concurrence 

 of causes gives rise to a new effect, bearing no relation to the separate 

 effects of those causes, the resulting phenomenon stands forth undisguised, 

 inviting attention to its peculiarity, and presenting no obstacle to our rec- 

 ognizing its presence or absence among any number of surrounding phe- 

 nomena. It admits, therefore, of being easily brought under the canons of 

 Induction, provided instances can be obtained such as those canons require; 

 and the non-occurrence of such instances, or the want of means to pro- 

 duce them artificially, is the real and only difficulty in such investigations ; 

 a difficulty not logical but in some sort physical. It is otherwise with cases 

 of what, in a preceding chapter, has been denominated the Composition of 

 Causes. There, the effects of the separate causes do not terminate and give 

 place to others, thereby ceasing to form any part of the phenomenon to be 

 investigated ; on the contrary, they still take place, but are intermingled 

 with, and disguised by, the homogeneous and closely allied effects of other 

 causes. They are no longer a, h, c, d, e, existing side by side, and continu- 

 ing to be separately discernible ; they are -j-a, —a,^b, —b,2b, etc. ; some of 



* Ante, chap, vii., § 1. / 



