Chap. XIII. CLASSIFICATION. 413 



genera descended from (I). So that we here have many 

 species descended from a single progenitor grouped into 

 genera ; and the genera are included in, or subordinate to, 

 sub-families, families, and orders, all united into one class. 

 Thus, the grand fact in natural history of the subordi- 

 nation of group under group, which, from its familiarity, 

 does not always sufficiently strike us, is in my judgment 

 fully explained. 



Naturalists try to arrange the species, genera, and 

 families in each class, on what is called the Natural 

 System. But what is meant by this system ? Some 

 authors look at it merely as a scheme for arranging to- 

 gether those living objects which are most alike, and for 

 separating those which are most unlike ; or as an artificial 

 means for enunciating, as briefly as possible, general pro- 

 positions, — that is, by one sentence to give the charac- 

 ters common, for instance, to all mammals, by another 

 those common to all carnivora, by another those com- 

 mon to the dog-genus, and then by adding a single sen- - 

 tence, 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 what else is meant by the plan 

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

 to our knowledge. Such expressions as that famous one 

 of Linnaeus, and which we often meet with in a more or 

 less concealed form, that the characters do not make the 

 genus, but that the genus gives the characters, seem to 

 imply that something more is included in our classifica- 

 tion, than mere resemblance. I believe that something 

 more is included ; and that propinquity of descent, — the 

 only known cause of the similarity of organic beings, — 

 is the bond, hidden as it is by various degrees of niodifi- 





