324 OPERATIONS SUBSIDIARY TO INDUCTION. 



animals and another may reasonably be considered 

 as mere modifications of the general phenomenon, 

 animal life ; modifications arising either from the dif- 

 ferent degrees 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 produced by the general laws of 

 life ; those laws still exercising a predominant influence 

 over the result. Such being the case, no other induc- 

 tive inquiry respecting animals can be successfully 

 carried on, except in subordination to the great inquiry 

 into the universal laws of animal life. And the clas- 

 sification of animals best suited to that one purpose, 

 is the most suitable to all the other purposes of zoo- 

 logical science. 



3. To establish a classification of this sort, or even 

 to comprehend it when established, requires the power 

 of recognising the essential similarity of a phenomenon, 

 in its minuter degrees and obscurer forms, with what 

 is called the same phenomenon in the greatest perfection 

 of its developement ; that is, of identifying with each 

 other all phenomena which differ only in degree, and 

 in properties which we suppose to be caused by differ- 

 ence of degree. In order to recognise this identity, or 

 in other words, this exact similarity of quality, the 

 assumption of a type-species is indispensable. We 

 must consider as the type of the class, that among the 

 Kinds included in it, which exhibits the properties 

 constitutive of the class, in the highest degree ; con- 

 ceiving the other varieties as instances of degeneracy, 

 as it were, from that type ; deviations from it by infe- 

 rior intensity of the characteristic property or proper- 

 ties. For every phenomenon is best studied (c&teris 

 paribus) where it exists in the greatest intensity. It 



