288 OPERATIONS SUBSIDIARY TO INDUCTION. 



the discovery of the conditions and laws of the general 

 phenomenon of life, w,hich is common to man with those 

 inferior animals. And they are, even, rightly considered as 

 properties of animated nature itself; because they may evidently 

 he affiliated to the general laws of animated nature; because 

 we may fairly presume that some rudiments or feehle degrees 

 of those properties would be recognised in all animals by more 

 perfect organs, or even by more perfect instruments, than ours ; 

 and because those may be correctly termed properties of a class, 

 which a thing exhibits exactly in proportion as it belongs to 

 the class, that is, in proportion as it possesses the main 

 attributes constitutive of the class. 



4. It remains to consider how the internal distri 

 bution of the series may most properly take place : in what 

 manner it should be divided into Orders, Families, and 

 Genera. 



The main principle of division must of course be natural 

 affinity ; the classes formed must be natural groups : and the 

 formation of these has already been sufficiently treated of. 

 But the principles of natural grouping must be applied in 

 subordination to the principle of a natural series. The groups 

 must not be so constituted as to place in the same group things 

 which ought to occupy different points of the general scale. 

 The precaution necessary to be observed for this purpose is, 

 that the primary divisions must be grounded not on all 

 distinctions indiscriminately, but on those which correspond 

 to variations in the degree of the main phenomenon. The 

 series of Animated Nature should be broken into parts at the 

 points where the variation in the degree of intensity of the 

 main phenomenon (as marked by its principal characters, 

 Sensation, Thought, Voluntary Motion, &c.) begins to be 

 attended by conspicuous changes in the miscellaneous pro 

 perties of the animal. Such well-marked changes take place, 

 for example, where the class Mammalia ends ; at the points 

 where Fishes are separated from Insects, Insects from Mol- 

 lusca, &c. When so formed, the primary natural groups will 

 compose the series by mere juxtaposition, without redistri- 



