INTERMIXTURE OF EFFECTS. 519 



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 inter- 

 ference of causes, where each cause continues to pro- 

 duce 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 consider- 

 ation. It presents, however, so far as direct induction 

 apart from deduction 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 at 

 least stands forth undisguised, inviting attention to its 

 peculiarity, and presenting no obstacle to our recog- 

 nising its presence or absence among any number of 

 surrounding phenomena. 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 produce 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 



