jnanam te ’ham sa-vijnanam
idam vaksyamy asesatah
yaj jnatva neha bhuyo ’nyaj
I shall now declare unto you in full this knowledge, both phenomenal and numinous. This being known, nothing further shall remain for you to know.
Commentary by Srila Prabhupada
Complete knowledge includes knowledge of the phenomenal world, the spirit behind it, and the source of both of them. This is transcendental knowledge. The Lord wants to explain the above-mentioned system of knowledge because Arjuna is Krishna’s confidential devotee and friend. In the beginning of the Fourth Chapter this explanation was given by the Lord, and it is again confirmed here: complete knowledge can be achieved only by the devotee of the Lord in disciplic succession directly from the Lord. Therefore one should be intelligent enough to know the source of all knowledge, who is the cause of all causes and the only object for meditation in all types of yoga practice. When the cause of all causes becomes known, then everything knowable becomes known, and nothing remains unknown. The Vedas (Mundaka Upanishad 1.3) say, kasmin bhagavo vijnate sarvam idam vijnatam bhavati.
Commentary by Sri Visvanatha Cakravarti Thakur
Before attaining the stage of attachment to me, the devotee understands (jnanam) about my powers. After that, he realizes (vijnanam) my sweetness. Hear about both of these. Knowing this, nothing else remains to be known, for knowledge and realization of my impersonal aspect are included in it.