“All this is verily Brahman. This Ātman (Self) is Brahman. This Ātman has four quarters.” All this is verily Brahman. All that has been said to consist merely of ĀŪṀ (in the previous mantra) is Brahman. That Brahman which has been described (as existing) inferentially is now pointed out as being directly known, by the passage, “This Self is Brahman”. The word this, meaning that which appears divided into four quarters, is pointed out as the innermost Self, with a gesture (of hand) by the passage,‘This is Ātman'. That Ātman indicated by ĀŪṀ, signifying both the higher and the lower Brahman, has four quarters (padas).  —Māṇḍūkya Upaniṣad Kārikā 1.2