CLASSIFICATION AND TUB PREDICABLES. 83 



nothing more than the JifTerence between those attributes' of the class 

 which are, and those which are not, involved in the signification of the 

 class-name. As applied to individuals, the word Essence, we found, 

 has no meaning, except in connexion with the exploded tenets of the 

 Realists ; and what the schoohnen chose to call the essence of an indi- 

 ^■idual,'wa6 simply the essence of the class to which that individual 

 was most familiarly referred. 



Is there no difference, then, except this merely verbal one, between 

 the classes which the schoolmen admitted to be genera or species, and 

 those to which they refused the title i Is it an error to regai"d some of 

 the differences which exist among objects as differences in kind (genere 

 or specie), and others oidy as differences in the accidents 1 Were the 

 schoolmen right or wrong in giving to some of tlie classes into which 

 things may be divided, the name of kinds, and considering others as 

 secondary divisions, grounded upon differences of a comparatively 

 supei-ficial nature ? Examination will show that the Aristotelians did 

 mean something by this distinction, and something important; but 

 which, being but indistinctly conceived, was inadequately expressed 

 by the phraseology of essences, and by the various other modes of 

 speech to which they had recourse. 



§ 4. It is a fundamental principle in logic, that the power of framing 

 classes is unlimited, as long as there is any (even the smallest) differ- 

 ence to found a distinction upon. Take any attribute whatever, and 

 if some things have it, and others have not, we may ground upon the 

 attribute a di^nsion of all things into two classes ; and we actually do 

 so, the moment we create a name which connotes the attribute. The 

 number of possible classes, therefore, is boundless ; and there are as 

 many actual classes (either of real or of imaginary things) as there are 

 general names, positive and negative together. 



But if we contemplate any one of the classes so fonned, such as the 

 class animal or plant, or the class sulphur or phosphorus, or the class 

 white or red, and consider in what particulars the individuals included 

 in the class differ from those which do not come within it, we find a 

 very remarkable diversity in this respect between some classes and 

 others. There are some classes, the things contained in which differ 

 from other things only in certain particulars which may be nmnbered ; 

 while others differ in more than can be numbered, more even than we 

 need ever expect to know. Some classes have little or nothing in 

 common to characterize them by, except precisely what is connoted 

 by the name : white things, for example, are not distii\guishcd by any 

 common properties except whiteness-; or if they are, it is only by such 

 as are in some way dependent upon, or connected with, whiteness. 

 But a hundred generations have not exhausted the common properties 

 of animals or of plants, of sulphur or of phosphorus ; nor do we suppose 

 them to be exhaustible, but proceed to new obsei-vations and experi- 

 ments, in the full confidence of discovering new properties which were 

 by no means implied in those we previously knew. Wliile, if any one 

 were to propose for investigation the common properties of all things 

 which are of the same color, the same shape, or the same specific 

 gravity, the absurdity would be palpable. We have no ground to 

 believe that any such common propeities exist, cXcejJt such as maybe 

 shown to be involved in the supjiosition itself, or to be derivable from 



