CLASSIFICATION AND THE PREDICABLES. 145 



or, as they further explain it, signifies an attribute which is 

 not 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 neces- 

 sarily be possessed by whatever comes under that definition. 

 Accidens, on the contrary, has no connexion whatever with 

 the essence, but may come and go, and the species still re- 

 main what it was before. If a species could exist without its 

 Propria, it must be capable of existing without that on 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 to be altered, since with them an Accidens has no 

 connexion. 



A Propriuin. therefore, of the species, may be defined, any 

 attribute which belongs to all the individuals included in the 

 species, and which, though 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 pur- 

 pose,) 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 Proprium. It may 

 follow as a conclusion follows premises, 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 straight 

 lines and parallel, and the number of sides four. The attri- 

 bute, therefore, of having the opposite sides equal, is a Pro- 

 prium of the class parallelogram; and a Proprium of the 

 first kind, which follows from the connoted attributes by way 

 of demonstration. The attribute of being capable of under- 

 standing language, is a Proprium of the species man, since 

 VOL. i. 10 



