DEFINITION. 191 



dental definition, or description, becomes on the par- 

 ticular occasion and for the particular purpose, a com- 

 plete and genuine definition. This actually occurs 

 with respect to one of the preceding examples, "Man is 

 a mammiferous animal having two hands," which is the 

 scientific definition of man considered as one of the 

 species in Cuvier's distribution of the animal kingdom. 



In cases of this sort, although the definition is 

 still a declaration of the meaning which in the parti- 

 cular instance the name is appointed to convey, it 

 cannot be said that to state the meaning of the word 

 is the purpose of the definition. The purpose is not 

 to expound a name, but to help to expound a classifi- 

 cation. The special meaning which Cuvier assigned 

 to the word Man, (quite foreign to its ordinary 

 meaning, though involving no change in the denota- 

 tion of the word,) was incidental to a plan of arranging 

 animals into classes on a certain principle,, that is, 

 according to a certain set of distinctions. And since 

 the definition of Man according to the ordinary conno- 

 tation of the word, though it would have answered 

 every other purpose of a definition, would not have 

 pointed out the place which the species ought to occupy 

 in that particular classification ; he gave the word a 

 special connotation, that he might be able to define it 

 by the kind of attributes upon which, for reasons of 

 scientific convenience, he had resolved to found his 

 division of animated nature. 



Scientific definitions, whether they are definitions 

 of scientific terms or of common terms used in a 

 scientific sense, are almost always of the kind last 

 spoken of: their main purpose is to serve as the 

 landmarks of scientific classification. And since the 

 classifications in any science are continually modified 

 as scientific knowledge advances, the definitions in the 



