Chap. XIV.] CLASSIFICATION. 205 



unlike ; or as an artificial method of enunciating, as 

 briefly as possible, general propositions, — that is, by one 

 sentence to give the characters common, for instance, to 

 all mammals, by another those common to all carnivora, 

 by another those common to the dog-genus, and then, 

 by adding a single sentence, a full description is given 

 of each kind of dog. The ingenuity and utility of this 

 system are indisputable. But many naturalists think 

 that something more is meant by the Natural System ; 

 they believe that it reveals the plan of the Creator ; 

 but unless it be specified whether order in time or 

 space, or both, or what else is meant by the plan of the 

 Creator, it seems to me that nothing is thus added to 

 our knowledge. Expressions such as that famous one 

 by Linnaeus, which we often meet with in a more or 

 less concealed form, namely, that the characters do not 

 make the genus, but that the genus gives the characters, 

 seem to imply that some deeper bond is included in our 

 classifications than mere resemblance. I believe that 

 this is the case, and that community of descent — the 

 one known cause of close similarity in organic beings — 

 is the bond, which though observed by various degrees 

 of modification, is partially revealed to us by our 

 classifications. 



Let us now consider the rules followed in classifica- 

 tion, and the difficulties which are encountered on the 

 view that classification either gives some unknown 

 plan of creation, or is simply a scheme for enunciating 

 general propositions and of placing together the forms 

 most like each other. It might have been thought 

 (and was in ancient times thoughfr) that those parts of 

 the structure which determined the habits of life, and 

 the general place of each being in the economy of 



