COMPOSITION OF CAUSES. 409 



case in which it is heterogeneous to them ; between laws which 

 work together without alteration, and laws which, when called 

 upon to work together, cease and give place to others ; is one 

 of the fundamental distinctions in nature. The former case, 

 that of the Composition of Causes, is the general one; the 

 other is always special and exceptional. There are no objects 

 which do not, as to some of their phenomena, obey the prin 

 ciple of the Composition of Causes ; none that have not some 

 laws which are rigidly fulfilled in every combination into 

 which the objects enter. The weight of a body, for instance, 

 is a property which it retains in all the combinations in which 

 it is placed. The weight of a chemical compound, or of an 

 organized body, is equal to the sum of the weights of the 

 elements which compose it. The weight either of the ele 

 ments or of the compound will vary, if they be carried farther 

 from their centre of attraction, or brought nearer to it ; but 

 whatever affects the one affects the other. They always 

 remain precisely equal. So again, the component parts of a 

 vegetable or animal substance do not lose their mechanical 

 and chemical properties as separate agents, when, by a peculiar 

 mode of juxtaposition, they, as an aggregate whole, acquire 

 physiological or vital properties in addition. Those bodies 

 continue, as before, 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 separate operation of the causes, the new laws, while 

 they supersede one portion of the previous laws, may coexist 

 with another portion, and may even compound 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 those 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 



