344 INDUCTION. 



cannot coexist unless it be because their causes coexist ; and the uni- 

 formity of coexistence, if such there be, between the effects, proves 

 that in the original collocation those particular causes, within the limits 

 of our observation, have uniformly been coexistent. 



§ 2. But these same considerations Compel us to recognize that there 

 must be one class of coexistences which cannot depend upon causation ; 

 the coexistences between the ultimate properties of things : between 

 those properties which are the causes of all phenomena, but are not 

 themselves caused by any phenomenon, and to find a cause for which, 

 we must ascend to the origin of all things. Yet among these ultimate 

 properties there are not only coexistences, but uniformities of coex- 

 istence. General propositions may be, and are formed, which assert 

 that whenever certain properties are found, certain others are found 

 along v\dth them. We perceive an object : say, for instance, water. 

 We recognize it to be water, of course, by certain of its properties. 

 Having recognized it, we are able to affiiTn of it innumerable other 

 properties ; which we could not do unless it were a general ti'uth, a 

 law or uniformity in nature, that the set of properties by which we 

 identified the substance as water, always have those other properties 

 conjoined with them. 



In a chapter of a fonner book, it has been explained in some detail 

 what is meant by the Kinds of objects,* those classes which differ from 

 one another not by a limited and definite, but by an indefinite and un- 

 known, number of distinctions. To this we have now to add, that 

 every proposition by which anything is asserted of a Khid, affirms an 

 unifoiTnity of coexistence. Since we know nothing of Kinds but their 

 properties, the Kind, to us, is the set of properties by which it is 

 identified, and which must of course be sufficient to distinguish it from 

 every other Kind.t In affirming anything, therefore, of a Kind, we are 

 affirming something to be unifoiTnly coexistent with the properties by 

 which the Kind is recognized ; and that is the sole meaning of the 

 assertion. 



Among the uniformities of coexistence which exist in nature, may 

 hence be numbered all the properties of Kinds. The whole of these, 

 however, are not independent of causation, but only a portion of them. 

 Some are ultimate properties, others derivative ; of some, no cause 

 can be assigned, but others are manifestly dependent upon causes. 

 Thus, atmospheric air is a Kind, and one of its most unequivocal 

 properties is its gaseous form : this property, however, has for its 

 cause the presence of a certain quantity of latent heat; and if that heat 

 could be taken away (as has been done from so many gases in Mr. 

 Faraday's experiments), the gaseous foi-m would doubtless disappear, 

 together with numerous other properties which depend upon, or are 

 caused by, that property. 



* Supra, book i., chap. vii. 



t In some cases, a Kind is sufficiently identified by some one remarkable property ; but 

 most commonly several are required ; each property, considered singly, being a joint 

 property of that and of other Kinds. The mere color and brightness of the diamond are 

 common to it with the paste from which false diamonds are made ; the double refraction is 

 common to it with Iceland spar, and many other stones ; but the color and brightness 

 and the double refraction together, iclentify its Kind ; that is, are a mark to us that it is 

 combustible ; that when burnt it produces carbonic acid ; that it cannot be cut with any 

 known substance ; together with many other ascertained properties, and the fact that 

 there exist an indefinite number still unascertained. 



