And every activity of the human being is to be considered a failure without having this inquiry in his mind. So persons who have awakened this inquiry into his mind as to "What I am, why I am suffering, wherefrom I have come or where I shall go after death," when these inquiries come, are awakened in the mind of a sane human being, then he is practically the right student for understanding Bhagavad-gītā. And he must be śraddhāvān. Śraddhāvān. He must have respect, a fond respect in the Supreme Personality of Godhead. Such a person, as the ideal person was Arjuna.
So Lord Kṛṣṇa, He descends, yadā yadā hi dharmasya glānir bhavati (BG 4.7), just to establish the real purpose of life. When man forgets the real purpose of life, the mission of human form of life, then it is called dharmasya glāniḥ, the disturbance of the occupation of human being.