82 THE SCIENCE OF LOGIC. 



we compare him with other beings endowed with intelligence 

 &quot; spiritual beings &quot; hisgenus will be &quot; spirit,&quot; his differentia &quot;em 

 bodied,&quot; and his definition &quot;embodied spirit&quot;. 1 In such cases 

 the difference in definition is not a real difference, for so long as 

 the species remains the same so will the specific nature or connota 

 tion. Moreover, in all such cases there is some one genus into which 

 the species in question naturally falls, and it is that genus with the 

 appropriate differentia that is regarded as the definition of the 

 species in question (51). 



The differentia we have been considering is the differentia 

 specifica that which differentiates the various cognate species of a 

 given genus. In reference to these latter, the differentia which 

 marks off their proximate genus from its cognate classes under a 

 higher genus, is called their generic differentia, i.e. the differentia 

 which, being common to them all, marks off their proximate genus 

 from other classes. Thus &quot; life &quot; would be the generic differentia 

 of &quot; plants &quot; and &quot; animals &quot; marking off their proximate genus, 

 &quot;living things,&quot; from &quot;inanimate things&quot;. 



So, also, we might give the name of differentia individua to the 

 whole group of characterizing traits and qualities (called insepar 

 able accidents of the individual 2 ), which serve to distinguish a 

 given individual from all other individuals in the same species 

 infima. Such &quot; individual accidents &quot; are therefore really as 

 essential to the concrete individual (considered as really existing 

 in concrete time and space) as the differentia specifica is to 

 the species. It is not in relation to the individual that they are 

 accidents or coincidences, but to the general characteristics we 

 have already apprehended in the individual (48). 



Proprium : The predication is said to be in the predicable 

 called proprium when the predicate gives an attribute (or group), 

 not included in the essence or connotation of the subject, but 

 following necessarily from it. Such an attribute is called a 

 property of the subject of which it is affirmed. Again, we may 

 distinguish between generic, specific, and individual propria. For 

 instance, &quot; endowed with a nervous system &quot; might be regarded 

 as a generic property of man, inasmuch as it is always found in 

 every man, though not in man alone, but in all the members 

 of his proximate genus &quot; animal &quot; : sensibility or sense con 

 sciousness (which is the differentia of &quot;animal&quot;) involving the 



1 WELTON, Logic, i., p. 109 ; JOSEPH, op. cit., pp. 68, 69. 



2 CLARKE, Logic, p. 183. 



