  A very well-represented philosophical genre is the compendium. Most of these cover only a part of philosophy, like the logic compendium by John Chortasmenos (c. 1370–1436/37), the Quadrivium by George Pachymeres (1242–c. 1310), or the Logic and Quadrivium by the anonymous of 1007 (‘Anonymus Heiberg’). Some of them attempt universality, like Pachymeres’ paraphrase-compendium of Aristotle’s philosophical writings (the Philosophia), or indeed Joseph Rhakendytes’ (died 1330) Encyclopedia, which also included rhetoric and medicine. As to the question of why the Byzantines produced compendia, there can be little doubt that they mainly did so for educational purposes. Most of the compendia are wholly or partly concerned with logic, the most basic subject in the philosophical curriculum. They do not contain detailed comments for people already initiated in the subtleties of Aristotelian logic; rather, they are introductory texts that do not presuppose any significant knowledge of the subject. 