526 INDUCTION. 



who studied terrestrial phenomena ; and had, indeed, been a 

 matter of great interest at a time when the idea of explaining 

 celestial facts by terrestrial laws was looked upon as the con- 

 founding of an indefeasible distinction. When, however, the 

 celestial motions were accurately ascertained, and the deduc- 

 tive processes performed, from which it appeared that their 

 laws and those of terrestrial gravity corresponded, those celes- 

 tial observations became a set of instances which exactly 

 eliminated the circumstance of proximity to the earth ; and 

 proved that in the original case, that of terrestrial objects, it 

 was not the earth, as such, that caused the motion or the 

 pressure, but the circumstance common to that case with the 

 celestial instances, namely, the presence of some great body 

 within certain limits of distance. 



6. There are, then, three modes of explaining laws of 

 causation, or, which is the same thing, resolving them into 

 other laws. First, when the law of an effect of combined 

 causes is resolved into the separate laws of the causes, together 

 with the fact of their combination. Secondly, when the law 

 which connects any two links, not proximate, in a chain of 

 causation, is resolved into the laws which connect each with 

 the intermediate links. Both of these are cases of resolving 

 one law into two or more ; in the third, two or more are 

 resolved into one : when, after the law has been shown to hold 

 good in several different classes of cases, we decide that what 

 is true in each of these classes of cases, is true under some 

 more general supposition, consisting of what all those classes 

 of cases have in common. We may here remark that this last 

 operation involves none of the uncertainties attendant on 

 induction by the Method of Agreement, since we need not 

 suppose the result to be extended by way of inference to any 

 new class of cases, different from those by the comparison of 

 which it was engendered. 



In all these three processes, laws are, as we have seen, 

 resolved into laws more general than themselves ; laws ex- 

 tending to all the cases which the former extended to, and 

 others besides. In the first two modes they are also resolved 



