Shankaracharya wrote the Bhagavad Gita and explained it in the framework of Adhvaita Vedanta, non-dual Vedanta. Ramanuja Acharya comes along three hundred years later to write his beautiful commentary on the book. Swami Abhedananda who was here in the Vedanta Society of New York,. many people do not know he has a complete commentary on the Bhag Cavad Gita. There are commentaries in many Indian languages and now a lot of commentaries in English.