CLASSIFICATION AND THE PBEDICABLES. 137 



should never think of inquiring what properties, unconnected 

 with Christianity either as cause or effect, are common to 

 all Christians and peculiar to them ; while in regard to all 

 Men, physiologists are perpetually carrying on such an 

 inquiry ; nor is the answer ever likely to be completed. Man, 

 therefore, we may call a species; Christian, or Mathematician, 

 we cannot. 



Note here, that it is by no means intended to imply that 

 there may not be different Kinds, or logical species, of man. 

 The various races and temperaments, the two sexes, and even 

 the various ages, may be differences of kind, within our mean- 

 ing of the term. I do not say that they are so. For in the 

 progress of physiology it may almost be said to be made out, 

 that the differences which really exist between different races, 

 sexes, &c., follow as consequences, under laws of nature, 

 from a small number of primary differences which can be pre- 

 cisely determined, and which, as the phrase is, account for all 

 the rest. If this be so, these are not distinctions in kind ; no 

 more than Christian, Jew, Mussulman, and Pagan, a difference 

 which also carries many consequences along with it. And in 

 this way classes are often mistaken for real Kinds, which are 

 afterwards proved not to be so. But if it turned out that the 

 differences were not capable of being thus accounted for, then 

 Caucasian, Mongolian, Negro, &c. would be really different 

 Kinds of human beings, and entitled to be ranked as species by 

 the logician; though not by the naturalist. For (as already 

 noticed) the word species is used in a different signification in 

 logic and in natural history. By the naturalist, organized 

 beings are not usually said to be of different species, if it is sup- 

 posed that they could possibly have descended from the same 

 stock. That, however, is a sense artificially given to the 

 word, for the technical purposes of a particular science. To the 

 logician, if a negro and a white man differ in the same manner 

 (however less in degree) as a horse and a camel do", that Is, if 

 their differences are inexhaustible, and not referrible to any 

 common cause, they are different species, whether they are 

 descended from common ancestors or not. But if their dif- 

 ferences can all be traced to climate and habits, or to some 



