Aristotle founded logic and wrote six treatises on logical matters including categories, interpretation, prior analytics, posterior analytics, topics, and sophistical refutations. Zeno founded Stoicism which developed a system of logic, ethics, and physics. Porphyry wrote Isagoge, a textbook on logic for over 1000 years. Avicenna and Averroes wrote commentaries on Aristotle's Organon. Aquinas presented commentaries on Aristotle's logic. Bacon wrote Novum Organum which detailed a new system of logic. Boole developed symbolic logic.