 Both of these works follow the pattern of the logica vetus, the “old logic” inherited from antiquity: Porphyry’s introduction to Aristotle, the Isagoge; Aristotle’s Categories and On Interpretation; Boethius’s Introduction to the Categorical Syllogism, Categorical Syllogisms, Hypothetical Syllogisms, On Topical Difference, and On Division. Abelard’s works cover the material presented in the old logic, though they do so in different ways. His Logica ‘ingredientibus’ is a close textual commentary on the old logic, though only some of it survives, namely the commentaries on the Isagoge, the Categories, On Interpretation, and On Topical Differences; his Dialectica is an independent treatise on dialectic that treats the same material thematically, though neither the beginning (covering the Isagoge and the start of the Categories) nor the ending (on division and definition) have been preserved. In addition, there are four lesser works on dialectic: