The general teaching of the Upanishads is not that the phenomenal
world is unreal, as is sometimes supposed: it emanates from the Absolute as sparks are emanated from fire or as a spider's web is woven out of itself by the spider. The `mortal' and the `formed' are as much part of the`partless' Brahman as are the `immortal' and `unformed'.
Completemonism is found in the relatively late Mandukya Upanishad, but this is atypical of both the Upanishads themselves and of most of the subsequent sacred literature. The conclusion that nothing at all is except the One is arrived at by analogy with sleep. In dreams the sleeper`emanates' an `objective' world out of himself, and since the microcosm is an exact replica of the macrocosm, it must be inferred that the world in which we live is Brahman's dream. In deep sleep (and in death), however,all becomes one; but this, according to the Mandukya, does not constitute unconsciousness but a `mass of wisdom, composed of bliss'. This, on the macrocosmic scale, corresponds to the Brahman-Atman in its capacity of creator of the world, the material cause from which the cosmic dream proceeds. 'This is the Lord of all, the knower of all, this is the InnerController, the womb of all, the origin and end of creatures.'
If, then, dreamless sleep in the microcosm corresponds to the Lord, the
efficient and material cause of the universe, in the macrocosm, then there must be a fourth state in addition to the waking state, dream, and
dreamless sleep which is absolutely identical with the Absolute One.
There is: and this fourth state:
has cognizance neither of what is inside nor what is outside, nor of both together; it is not a mass of wisdom, it is not wise nor yet unwise. It is unseen; there can be no commerce with it; it is impalpable, has no
characteristics, unthinkable; it cannot be designated. Its essence is its firm conviction of the oneness of itself; it causes the phenomenal world to cease; it is tranquil and mild, devoid of duality. Such do they consider this fourth to be. He is the Self; he is who should be known.
This is the extreme form of the Brahman-Atman identification. The
ground of the objective universe and the essential human soul are
absolutely and identically one. All terms referring to the Absolute in the earlier Upanishads that suggest action, will, or intellect-such terms as `Inner Controller', Lord, King, or God, are no more than weak
approximations to an ineffable reality, the only correct formulation of which is `One without the second'.