440 OPERATIONS SUBSIDIARY TO INDUCTION. 



those gi'oups con-espond to Kinds wherever it is possible, but in most 

 cases without any such guidance. And in dohig this it is true that we 

 are naturally and properly guided, in most cases at least, by resem- 

 blance to a type. We form our groups round certain selected Kinds, 

 each of which serves as a sort of exemplar of its group. But though 

 the groups are suggested by types, I calnnot agree with Mr. Whewell 

 that a group when formed is determined by the type ; that in deciding 

 whether a species belongs to the group, a reference is made to the 

 type, and not to the characters; that the characters "cannot be ex- 

 pressed in words." This assertion is inconsistent with Mr. Wliewell's 

 own statement of the fundamental principle of classification, namely, 

 that " general assertions shall be possible." If the class did not possess 

 any characters in common, what general assertions would be possible 

 respecting it? Except that they all resemble each other more than 

 they resemble anything else, nothing whatever could be predicated of 

 the class. 



The truth is, on the contrary, that every genus or family is framed 

 with distinct reference to certain characters, and is composed, first and 

 principally, of species which agree in jjossessing all those characters. 

 To these are added, as a sort of appendix, such other species, gener- 

 ally in small number, as possess nearly all the properties selected; 

 wanting, some of them one property, some another, and which, while 

 they agree with the rest almost as much as these agree with one 

 another, do not resemble in an equal degree any other group. Our 

 conception of the class continues to be grounded on the characters; 

 and the class might be defined, those things which either possess that 

 set of characters, or resemble the things that do so,- more than they 

 resemble anything else. 



And this resemblance itself is not, like resemblance between simple 

 sensations, an ultimate fact unsusceptible of analysis. Even the inferior 

 degree of resemblance is created by the possession of common char- 

 acters. Whatever resembles the genus Rose more than it resembles 

 any other genus, does so because it possesses a greater number of the 

 characters of that genus, than of the characters of any other genus. 

 Nor can there be the smallest difficulty in representing, by an enumera- 

 tion of characters, the nature and degree of the resemblance which is 

 sti-ictly sufficient to include any object in the class. There are always 

 some properties common to all things which are included. Others 

 there often are, to which some things, which are nevertheless included, 

 are exceptions. But the objects which are exceptions to one character 

 ai'e not exceptions to another: the resemblance which fails in some 

 particulars must be made up for in others. The class, therefore, is 

 constituted by the possession of all the characters which are universal, 

 and viost of those which admit of exceptions. If a plant had the 

 ovules erect, the stigmata divided, the albumen not obliterated, and 

 was without stijaules, it probably would not be classed among the 

 RosaceEe. But it may want any one, or more than one of those char- 

 acters, and not be excluded. The ends of a scientific classification are 

 better answered by including it. Since it agrees so nearly, in its known 

 properties, with the sum of the characters of the class, it is likely to 

 resemble that class more than any other in those of its properties which 

 are still undiscovered. 



Not only, therefore, are natural groups, no less than any artificial 



