The Lord tells Arjuna that basically there is no possibility of understanding the Supreme Truth, the Absolute Truth, the Supreme Personality of Godhead, simply by speculating, for the Supreme Truth is so great that it is not possible to understand Him or to achieve Him simply by making a mental effort. Man can go on speculating for several millions of years, and if he is not devoted, if he is not a lover of the Supreme Truth, he will never understand Krishna, or the Supreme Truth. Only by devotional service is the Supreme Truth, Krishna, pleased, and by His inconceivable energy He can reveal Himself to the heart of the pure devotee. The pure devotee always has Krishna within his heart; and with the presence of Krishna, who is just like the sun, the darkness of ignorance is at once dissipated. This is the special mercy rendered to the pure devotee by Krishna