Ibn Sina wrote extensively on early Islamic philosophy, especially the subjects logic, ethics, and metaphysics, including treatises named Logic and Metaphysics. Most of his works were written in Arabic then the language of science in the Middle East and some in Persian. Of linguistic significance even to this day are a few books that he wrote in nearly pure Persian language (particularly the Danishnamah-yi 'Ala', Philosophy for Ala' ad-Dawla'). Ibn Sina's commentaries on Aristotle often criticized the philosopher,[citation needed] encouraging a lively debate in the spirit of ijtihad.
What is one subject that Ibn SIna specialized in?
ethics