‘Logic’ explores Aristotle’s syllogistic. In the Prior Analytics Aristotle uses ‘proposition’ for simple sentences and ‘term’ for their salient parts. Thus a proposition affirms or denies something of something, and the two things are its terms. The thing affirmed or denied is the ‘predicate’ of the proposition, and the thing of which the predicate is affirmed or denied is the ‘subject’ of the proposition. In Aristotle’s logic, propositions are all either universal or particular. Aristotle’s logic thus concerns itself with four types of proposition: universal affirmatives; universal negatives; particular affirmatives; and particular negatives. To achieve generality, rather than employing particular terms to describe and characterize arguments, Aristotle used letters.