476 



OPERATIONS SUBSIDIARY TO INDUCTION. 



animal life, the first step, after form- 

 ing the most distinct conception of 

 the phenomenon itself possible in the 

 existing state of our knowledge, is to 

 rrect into one great class (that of ani- 

 mals) all the known Kinds of beings 

 where that phenomenon presents it- 

 self, in however various combinations 

 with other properties, and in how- 

 ever different degrees. As some of 

 these Kinds manifest the general 

 phenomenon of animal life in a very 

 high degree, and others in an insig- 

 nificant degree, barely sufficient for 

 recognition, we must, in the next 

 place, arrange the various Kinds in a 

 series, following one another accord- 

 ing to the degrees in which they 

 severally exhibit the phenomenon ; 

 beginning therefore with man, and 

 ending with the most imperfect kinds 

 of zoophytes. 



This is merely saying that we should 

 put the instances from which the law 

 is to be inductively collected into the 

 order which is implied in one of the 

 four Methods of Experimental In- 

 quiry discussed in the preceding Book, 

 the fourth Method, that of Concomi- 

 tant Variations. As formerly re- 

 marked, this is often the only method 

 to which recourse can be had, with 

 assurance of a true conclusion, in 

 cases in which we have but limited 

 means of effecting, by artificial ex- 

 periments, a separation of circum- 

 stances Tisually conjoined. The prin- 

 ciple of the method is, that facts 

 which increase or diminish together, 

 and disappear together, are either 

 cause and effect, or effects of a com- 

 mon cause. When it has been as- 

 certained that this relation really 

 subsists between the variations, a 

 connection between the facts them- 

 selves may be confidently laid down, 

 either as a law of nature or only as 

 an empirical law, according to cir- 

 cumstances. 



That the application of this IMethod 

 must be preceded by the formation of 

 such a series as we have described, is 

 too obvious to need being pointed out; 

 and the mere arrangement of a set of 



objects in a series, according to the 

 degrees in which they exhibit some 

 fact of which we are seeking the law, 

 is too naturally suggested by the 

 necessities of our inductive opera- 

 tions to require any lengthened illus- 

 tration here. But there are cases in 

 which the arrangement required for 

 the special purpose becomes the de- 

 termining principle of the classifica- 

 tion of the same objects for general 

 purposes. This will naturally and 

 properly happen when those laws of 

 the objects which are sought in the 

 special inquiry enact so principal a 

 part in the general character and 

 history of those objects — exercise so 

 much influence in determining all the 

 phenomena of which they are either 

 the agents or the theatre — that all 

 other differences existing among the 

 objects are fittingly regarded as mere 

 modifications of the one phenomenon 

 sought — effects determined by the 

 co-operation of some incidental cir- 

 cumstance with the laws of that phe- 

 nomenon. Thus in the case of ani- 

 mated beings, the differences between 

 one class of animals and another may 

 reasonably be considered as mere 

 modifications of the general pheno- 

 menon, animal life — modifications 

 arising either from the different de- 

 grees in which that phenomenon is 

 manifested in different animals, or 

 from the intermixture of the effects 

 of incidental causes peculiar to the 

 nature of each, with the effects pro- 

 duced by the general laws of life, 

 those laws still exercising a predomi- 

 nant influence over the result. Such 

 being the case, no other inductive in- 

 quiry respecting animals can be suc- 

 cessfully carried on, except in subor- 

 dination to the great inquiry into the 

 universal laws of animal life ; and the 

 classification of animals best suited to 

 that one purpose is the most suitable 

 to all the other purposes of zoological 

 science. 



§ 3. To establish a classification of 

 this sort, or even to apprehend it when 

 established, requires the power of re- 



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