Logical diagrams in the pons asinorum

This paper provides textual basis for the traditional lune-and-triangle diagrams that accompany Aristotle’s logical texts in Latin and Byzantine traditions. I show how Prior Analytics I 27–28 provide a spatial configuration in which terms are set out and which produce the lune-and-triangle diagrams when rearranging the terms in order to have a common term between the lists for the predicate and the lists for the subject. Under this interpretation, Aristotle’s diagrams for syllogistic have never been lost, they provide a coherent understanding of perfect syllogisms.