CLASSIFICATION AND THE PREDICABLES. 179 



indeed part of the essence, but which flows from, or 

 is a consequence of, the essence, and is, therefore, 

 inseparably attached to the species ; e. g., the various 

 properties of a triangle, which, though no part of its 

 definition, must necessarily be possessed by whatever 

 comes under that definition. Accidens, on the con- 

 trary, has no connexion whatever with the essence, 

 but may come and go, and the species still remain 

 what it was before. If a species could exist without 

 its Propria, it must be capable of existing without that 

 upon which its Propria are necessarily consequent, 

 and therefore without its essence, without that which 

 constitutes it a species. But an Accidens, whether 

 separable or inseparable from the species in actual 

 experience, may be supposed separated, without the 

 necessity of supposing any other alteration ; or at 

 least, without supposing any of the essential properties 

 of the species altered, since with them an Accidens has 

 no connexion. 



A Proprium, therefore, of the species, may be 

 defined, any attribute which belongs to all the indi- 

 viduals included in the species, and which, although 

 not connoted by the specific name (either ordinarily 

 if the classification we are considering be for ordinary 

 purposes, or specially if it be for a special purpose), 

 yet follows from some attribute which the name either 

 ordinarily or specially connotes. 



One attribute may follow from another in two 

 ways ; and there are consequently two kinds of Pro- 

 prium. It may follow as a conclusion follows pre- 

 misses, or it may follow as an effect follows a cause. 

 Thus, the attribute of having the opposite sides equal, 

 which is not one of those connoted by the word 

 Parallelogram, nevertheless follows from those con- 

 noted by it, namely, from having the opposite sides 



N -2 



