310 INDUCTION. 



cannot observe with what circumstances it is attended, or according to 

 what laws it produces its effects. The production of water, that is, of 

 the sensible phenomena which characterize the compound, may be a 

 very remote effect of those laws. There may be innumerable inter- 

 vening links; and we are sure that there must be some. Having full 

 proof that corpuscular action of some kind takes place previous to any 

 of the great transformations in the sensible properties of substances, 

 we can bave no doubt that the laws of chemical action, as at present 

 knowTi, are not ultimate but derivative laws; however ignorant we 

 may be, and even though we should for ever remain ignorant, of the 

 nature of the laws of corpuscular action from which they are derived. 



In like manner all the processes of vegetative life, whether in the 

 vegetable properly so called or in the animal body, are corpuscular 

 processes. Nutrition is the addition of particles to one another, in 

 part replacing other particles separated and excreted, in part occasion- 

 ing an increase of bulk or weight, so gradual, that only after a long 

 continuance does it become perceptible. Various organs, by means 

 of peculiar vessels, secrete from the blood, fluids, the component par- 

 ticles of which must have been in the blood, but which differ from it 

 most widely both in 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 com- 

 binations of corpuscles. 



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

 unresolved, may be infeiTed to be a derivative law, is any indication 

 of the existence of an intermediate link or links between the antece- 

 dent 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 ante- 

 cedent is the sum of many homogeneous, in the other of heterogeneous, 

 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 proportion to their quantity of matter. All true propositions, there- 

 fore, which can be made concerning gravity, are derivative laws ; the 

 ultimate law into which they are all resolvable being that every par- 

 ticle of matter atti'acts 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 here a com- 

 plex phenomenon, made up of heterogeneous elements; the columu 

 of the atmosphere over any particular place consisting of two parts, a 

 column of air, and a column of aqueous vapor mixed with it ; and the 

 change in the two together, manifested by a fall of the barometer, and 

 followed by rain, must be either a change in one of these, or in the 

 other, or in both. We might, then, even in the absence of any other 

 evidence, form a reasonable presumption, fi'om the invariable presence 



