Series 1, Chapter 20 pg 205, Para 2: The higher knowledge we then get is that which is to the knower of Brahman his constant vision of things when he lives uninterruptedly in the Brahman, brahmavid brahmani sthitah. That is not a vision or knowledge or consciousness of Brahman to the exclusion of all else, but a seeing of all in Brahman and as the Self. For, it is said, the knowledge by which we rise beyond all relapse back into the bewilderment of our mental nature, is “that by which thou shalt see all existences without exception in the Self, then in Me.” Elsewhere the Gita puts it more largely, …

Series 1, Chapter 23 pg 236, Para 1: Brahman-knower who has risen into the Brahman-consciousness, brahmavid brahmani sthitah, develops in nine verses that follow its idea of Brahmayoga and of Nirvana in the Brahman. “When the soul is no longer attached to the touches of outward things,” it begins, “then one finds the happiness that exists in the Self; such a one enjoys an imperishable happiness, because his self is in Yoga, yukta, by Yoga with the Brahman.” The non-attachment is essential, it says, in order to be free from the attacks of desire and wrath and passion, a freedom without which true happiness is not possible. That happiness and that equality are to be gained entirely by man in the body: he is not to suffer any least remnant of the subjection to the troubled lower nature to remain in the idea that the perfect release will come by a putting off of the body; a perfect spiritual freedom is to be won here upon earth and possessed and enjoyed in the human life, prak sarira-vimoksanat. It then continues, “He who has the inner happiness and the inner ease and repose and the inner light, that Yogin becomes the Brahman and reaches self-extinction in the Brahman, brahma-nirvanam.” Here, very clearly, Nirvana means the extinction of the ego in the higher spiritual, inner Self, that which is for ever timeless, spaceless, not bound by the chain of cause and effect and the changes of the world-mutation, self-blissful, self-illumined and for ever at peace. The Yogin ceases to be the ego, the little person limited by the mind and the body; he becomes the Brahman; he is unified in consciousness with the immutable divinity of the eternal Self which is immanent in his natural being.