Lord Krishna explains that he is the supreme truth and cause of all existence, both material and spiritual. However, only a few advanced souls who surrender to him with devotion are able to truly know and understand him. Out of many thousands who endeavor for spiritual perfection, very few achieve it, and among those who do, hardly anyone knows Krishna in truth as the supreme personality of Godhead. Krishna promises to fully explain to Arjuna both phenomenal and spiritual knowledge, so that nothing further remains for him to know.