Krishna's personality is so great, His intelligence is so deep and His purpose is so inconceivable, that a devotee realizes he can never fully understand Krishna. That is one realization of Krishna, that Krishna is beyond understanding by blind material senses. Krishna is adhoksaja, which means that He cannot be understood simply by some material formulas, He can only be understood by devotion. Without devotion to Krishna it is not possible to understand anything about Him.
March 8, 1991, Izori