People are too much engrossed with the body. That is called materialism. But when you understand what is spirit and you act accordingly, that is called spiritualism. So Arjuna was hesitating to fight with the other party because he had bodily relationship with them. So between Arjuna and Kṛṣṇa there was discussion, but that was friendly discussion. Therefore, when Arjuna understood that simply friendly discussion could not solve the problem, he became His disciple. Kṛṣṇa... Arjuna surrendered to Kṛṣṇa, śiṣyas te 'ham śādhi māṁ prapannam: (BG 2.7) "My dear Kṛṣṇa, so long we are talking as friend. Now I become Your regular disciple. Kindly save me by instruction. What I have to do?" Therefore, when this stage was arrived, Kṛṣṇa is advising Arjuna as follows: śrī-bhagavān uvāca. Now, it is said here... Who is saying to Arjuna? The author or the recorder of Bhagavad-gītā... Bhagavad-gītā was spoken by Kṛṣṇa. It was a discussion between Kṛṣṇa and Arjuna, and it was recorded by Vyāsadeva, and later on it became a book. Just like when we speak it is recorded and later on it is published as a book. Therefore in this book it is said, bhagavān uvāca. Vyāsadeva is the writer. He does not say that, "I speak." He says, bhagavān uvāca, means "The Supreme Personality of Godhead said."
So Kṛṣṇa is accepted by the authorities as Bhagavān, or the Supreme Personality of Godhead. And what is Bhagavān? Bhagavān means that one who is fully equipped with six opulences. Fully equipped with all opulences means Bhagavān is the richest personality. How much rich Bhagavān, or God, is, we can understand that we are proud of possessing a few acres of land, and Bhagavān means who is the proprietor of the whole universe. Therefore He is considered the richest. Similarly, He is considered the strongest. And similarly, He is considered the wisest.