what is there to tell us that the predicate is to be regarded in the one case as a species and in the other as an accident of the subject? Nothing plainly but the assumption of a definition already known. § 330. But if this assumption be granted, the classification seems to admit of a more or less complete defense by logic. For, given any subject, we can predicate of it either a class or an attribute. When the predicate is a class, the term predicated is called a Genus, if the subject itself be a class, or a Species, if it be an individual. When, on the other hand, the predicate is an attribute, the attribute predicated may be either the very attribute which distinguishes the subject from other members of the same class, in which case it is called the Difference, or it may be some attribute connected with the definition, i.e. Property, or not connected with it, i.e. Accident. § 331. These results may be exhibited in the following scheme-- Predicate ________________|_________________ | | Class Attribute ______|_______ __________|________ | | | | (Subject a (Subject a (The (Not the common singular distinguishing distinguishing term) term) Attribute) attribute) Genus Species Difference |___________________ | | (Connected (Not connected with the with the definition) definition) Property Accident § 332. The distinction which underlies this division between predicating a class and predicating an attribute (in quid or in quale) is a perfectly intelligible one, corresponding as it does to the grammatical distinction between the predicate being a noun substantive or a noun adjective. Nevertheless it is a somewhat arbitrary one, since, even when the predicate is a class-name, what we are concerned to convey to the mind, is the fact that the subject possesses the attributes which are connoted by that class-name. We have not here the difference between extensive and intensive predication, since, as we have already seen (§ 264), that is not a difference between one proposition and another, but a distinction in our mode of interpreting any and every proposition. Whatever proposition we like to take may be read either in extension or in intension, according as we fix our minds on the fact of inclusion in a class or the fact of the possession of attributes.