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