EMPIRICAL LAWS. 51 



mechanical properties and in chemical composition. 

 Here, then, are abundance of unknown links to be 

 filled up ; and there can be no doubt that the laws 

 of the phenomena of vegetative or organic life are 

 derivative laws, dependent upon properties of the 

 corpuscles, and of those elementary tissues which 

 are comparatively simple combinations of corpuscles. 



The first sign, then, from which a law of causation, 

 though hitherto unresolved, may be inferred to be a 

 derivative law, is any indication of the existence of an 

 intermediate link or links between the antecedent and 

 the consequent. The second is, when the antecedent 

 is an extremely complex phenomenon, and its effects, 

 therefore, probably, in part at least, compounded of 

 the effects of its different elements; since we know 

 that the case in which the effect of the whole is not 

 made up of the effects of its parts, is exceptional, the 

 Composition of Causes being by far the more ordinary 

 case. 



We will illustrate this by two examples, in one of 

 which the antecedent is the sum of many homo- 

 geneous, in the other of heterogenous, parts. The 

 weight of a body is made up of the weights of its 

 minute particles; a truth which astronomers express 

 in its most general terms, when they say that bodies, 

 at equal distances, gravitate to one another in propor- 

 tion to their quantity of matter. All true propo- 

 sitions, therefore, which can be made concerning 

 gravity, are derivative laws ; the ultimate law into which 

 they are all resolvable being that every particle of 

 matter attracts every other. As our second example, 

 we may take any of the sequences observed in 

 meteorology: for instance, that a diminution of the 

 pressure of the atmosphere (indicated by a fall of the 

 barometer) is followed by rain. The antecedent is 



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