"AUM That exists," is thus pointed out when arriving at the oneness of the Self and the Absolute;
With conceptual structures and the rest completely abandoned, this is what is said to be supreme wisdom.
Commentary
Supreme wisdom is the same as unconditioned wisdom whereby all conceptual structures which are a hindrance to attaining the Self-Absolute are completely abandoned. The Self and the Absolute are one, not two, as the Brihadaranyaka Upanishad (II.5.19) declares, "This Self is the Absolute," and the Chandogya Upanishad (VIII.14) re-affirms, "That (Absolute) is the Self." Sankaracharya in his commentary on the Katha Upanishad (I.2.15) says, "this AUM is a symbol." So AUM is the Self-Absolute.
This supreme wisdom is also affirmed in the Linga Purana. "The wisdom of the Absolute is supreme wisdom." Such wisdom is what underlines the Great Utterances of the Upanishads and other spritual texts. "AUM That exists": "That" is the Self-Absolute which is all that truly "exists" or has existence, but not as a conceptual structure, not as an object or an idea conceived by the conditioned mind to cogitate on and transmit to others.
When the sage declares, "arriving at the oneness of the Self and the Absolute," he means that one has arrived at spiritual freedom, which is the avowed goal of all philosophies and disciplines. Attaining the Self-Absolute is the same as experiencing the Self-Absolute under whatever name this goes by. Such an individual is described by Narayana Guru in the final chapter. The Suta Gita gives a fine description of the attained person:
"He should know that the totality which appears different from the Self is his Self, and completely convinced by his own experience that he is the pure, non-dual Absolute, he should merge that conviction in his pure unconditioned consciousness which is non-changing and non-dual."