COMPOSITION OF CAUSES. 269 



to obey mechanical and chemical laws, in so far as the operation of those 

 laws is not counteracted by the new laws which govern them as organized 

 beings ; when, in short, a concurrence of causes takes place which calls into 

 action new laws bearing no analogy to any that we can trace in the sepa- 

 rate operation of the causes, the new laws, while they supersede one portion 

 of the previous laws, may co-exist with another portion, and may even com- 

 pound the effect of those previous laws with their own. 



Again, laws which were themselves generated in the second mode, may 

 generate others in the first. Though there are laws which, like tliose of 

 chemistry and physiology, owe their existence to a breach of the principle 

 of Composition of Causes, it does not follow that these peculiar, or, as they 

 might be termed, heteropathic laws, are not capable of composition with 

 one another. The causes which by one combination have had their laws 

 altered, may carry their new laws with them unaltered into their ulterior 

 combinations. And hence there is no reason to despair of ultimately raising 

 chemistry and physiology to the condition of deductive sciences ; for though 

 it is impossible to deduce all chemical and j)hysiological truths from the 

 laws or properties of simple substances or elementary agents, they may 

 possibly be deducible from laws which commence when these elementary 

 agents are brought together into some moderate number of not very com- 

 plex combinations. The Laws of Life will never be deducible from the 

 mere laws of the ingredients, but the pi'odigiously complex Facts of Life 

 may all be deducible from comparatively simple laws of life ; which laws 

 (depending indeed on combinations, but on comparatively simple combi- 

 nations, of antecedents) may, in more complex circumstances, be strictly 

 compounded with one another, and with the physical and chemical laws of 

 the ingi'edients. The details of the vital phenomena, even now, afford innu- 

 merable exemplifications of the Composition of Causes ; and in proportion 

 as these phenomena are more accurately studied, there appears more reason 

 to believe that the same laws which operate in the simpler combinations 

 of circumstances do, in fact, continue to be observed in the more complex. 

 This will be found equally true in the phenomena of mind ; and even in 

 social and political phenomena, the results of the laws of mind. It is in 

 the case of chemical phenomena that the least progress has yet been made 

 in bringing the special laws under general ones from which they may be 

 deduced ; but there are even in chemistry many circumstances to encourage 

 the hope that such general laws will hereafter be discovered. The differ- 

 ent actions of a chemical compound will never, undoubtedly, be found to 

 be the sums of the actions of its separate elements ; but there may exist, 

 between the propei'ties of the compound and those of its elements, some 

 constant relation, which, if discoverable by a sufficient induction, would en- 

 able us to foresee the sort of compound which will result from a new com- 

 bination before we have actually tried it, and to judge of what sort of el- 

 ements some new substance is compounded before we have analyzed it. 

 The law of definite proportions, first discovered in its full generality by 

 Dalton, is a complete solution of this problem in one, though but a second- 

 ary aspect, that of quantity ; and in respect to quality, we have already 

 some partial generalizations, sufficient to indicate the possibility of ulti- 

 mately proceeding farther. We can predicate some common properties 

 of the kind of compounds which result from the combination, in each of the 

 small number of possible proportions, of any acid whatever with any base. 

 We have also the curious law, discovered by Berthollet, that two soluble 

 salts mutually decompose one another whenever the new combinations 



