  Although other commentaries on the categories were written shortly after Kilwardby's Commentary (such as those written by Peter of Spain, Roger Bacon, Nicholas of Paris, and Johannes Pagus), the most important commentary was by Albertus Magnus. Albertus wrote approximately seventy works, not counting his sermons and letters. A large number of these were commentaries on the extant works of Aristotle available to him at the time.  Nine of these works are devoted to logic, and of these, six are commentaries on Aristotle's Organon. However, within these commentaries, there is strong inclination towards a Neo–Platonic ontology which he barely manages to keep apart from logic.  