DEFINITION. 189 



distinguishes the species intended to be defined from 

 all other species of the same genus, but all the attri- 

 butes implied in the name of the species, which the 

 name of the superior genus has not already implied. 

 The assertion, however, that a definition must of 

 necessity consist of a genus and differentiae, is not 

 tenable. It was early remarked by logicians, that the 

 summum genus in any classification, having no genus 

 superior to itself, could not be defined in this manner. 

 Yet we have seen that all names, except those of our 

 elementary feelings, are susceptible of definition in the 

 strictest sense; by setting forth in words the con- 

 stituent parts of the fact or phenomenon, of which 

 the connotation of every word is ultimately composed. 



5. Although the first kind of imperfect defini- 

 tion, (which defines a connotative term by a part only 

 of what it connotes, but a part sufficient to mark out 

 correctly the boundaries of its denotation), has been 

 considered by the ancients, and by logicians in general, 

 as a complete definition ; it has always been deemed 

 necessary that the attributes employed should really 

 form part of the connotation ; for the rule was that 

 the definition must be drawn from the essence of the 

 class ; and this would not have been the case if it had 

 been in any degree made up of attributes not con- 

 noted by the name. The second kind of imperfect 

 definition, therefore, in which the name of a class is 

 defined by any of its accidents, that is, by attributes 

 which are not included in its connotation, has been 

 rejected from the rank of genuine Definition by all 

 philosophers, and has been termed Description. 



This kind of imperfect definition, however, takes 

 its rise from the same cause as the other, namely, the 

 willingness to accept as a definition anything which, 



