The Lord was acting as the spiritual master of Arjuna. Therefore it was His duty to inquire from Arjuna whether he understood the whole Bhagavad-gita in its proper perspective. If not, the Lord was ready to re-explain any point, or the whole Bhagavad-gita if so required. Actually, anyone who hears Bhagavad-gita from a bona fide spiritual master like Krsna or His representative will find that all his ignorance is dispelled. Bhagavad-gita is not an ordinary book written by a poet or fiction writer; it is spoken by the Supreme Personality of Godhead. Any person, if he is fortunate enough to hear these teachings from Krsna or from His bona fide spiritual representative, is sure to become a liberated person and get out of the darkness of ignorance.