CLASSIFICATION AND THE PREDICABLES. 87 



anything which caused it to have them. Logicians, liowever, not hking 

 to admit this, and being unable to detect what made the thing to be 

 what it was, satisfied themselves with what made it to be what it was 

 called. Of the innumerable properties, known and unknown, that are 

 connnon to the class man, a j)oition oidy, and of course, a very small 

 portion, are connoted by its name: these few, however, will naturally 

 have been thus distinguished fioni the rest cither for their gi'eater 

 obviousness, or for greater su^iposed importance. These proiieities, 

 then, which were connoted by the name, logicians seized upon, and 

 called them the essence of the species ; and not stopping there, they 

 affirmed them, in the case of the infima species, to be the essence of the 

 iuvAisadual too; for it was their maxim, that the species contained the 

 "_ whole essence" of the thing. Metaphysics, that fertile field of delu- 

 sion propagated by language, does not afford a more signal instance of 

 such delusion. On this account it was that rationality, being connoted 

 by the name man, was allowed to be a differentia of the class ; but the 

 peculiarity of cooking their food, not being connoted, was relegated to 

 the class of accidental properties. 



The distinction, therefore, between Differentia, Proprium, and Acci- 

 dens, is not founded in the nature of things, but in the connotation of 

 names; and we must seek it there if we wish to find what it is. 



From the fact that the genus includes the species, in other words, 

 <^fiiotes more than the species, or is predicable of a greater number of 

 individuals, it follows that the species must connote more than the 

 genus. It must connote all the attributes which the genus connotes, 

 or there would be nothing to prevent it fi-om denoting individuals not 

 included in the genus. And it must connote something besides, other- 

 wise it would include the whole genus. Animal denotes all the indi- 

 viduals denoted by man, and many more. Man, therefore, must coji- 

 note all that animal connotes, otherwise there might be men who were 

 not animals ; and it must connote something more than animal connotes, 

 otherwise all animals would be men. This surplus of connotation — this 

 which the species connotes over and above the connotation of the genus 

 — is the Differentia, or specific difference ; or, to state the same prop- 

 osition in other words, the Differentia is that, which must be added 

 to the connotation of the genus, to complete the connotation of the 

 species. 



The word man, for instance, exclusively of what it connotes in com- 

 mon with animal, also connotes rationality, and at least some approxi- 

 mation to that external form, which we all know, but which, as we 

 have no name for it considered in itself, we are content to call the 

 human. The differentia, or specific difference, therefore, of man, as 

 referred to the genus animal, is that outward form and the possession 

 of reason. The Aristotehans said, the possession of reason, without 

 the outward form. But if they adhered to this, they would have been 

 obliged to call the Houyhnhms men. The question never arose, and 

 they were never called upon to decide how such a case would have 

 affected their notion of essentiality. But, so far as it is possible to 

 determine how language would be used in a case which is purely 

 imaginary, we may say that the Houyhnhms would not be called men, 

 and that the term man, therefore, rc(juiros other conditions besides 

 rationality. The schoolmen, however, were satisfied with taking such 

 a portion of the differentia as sufficed to distinguish the species from 



