Twelve verses. That is all.
The Mandukya Upanishad is the shortest of the principal Upanishads — twelve verses that can be read in minutes and contemplated for a lifetime.
It begins without preamble: Om — this syllable is all this. All that was, is, and will be — all of it is Om. And what is beyond the three times is also Om.
Then it maps consciousness onto the syllable. Four states. Four aspects of Om. Four dimensions of what you are.
Jagrat — Waking. The first letter A. The waking state, in which consciousness moves outward through the seven limbs and nineteen mouths to experience the gross world. This is the state you know best — the state you think is most real.
Svapna — Dreaming. The second letter U. The dream state, in which consciousness turns inward and creates an entire world from its own substance. The dream feels real while you are in it. When you wake, it vanishes without a trace. What does this tell you about the waking world?
Sushupti — Deep Sleep. The third letter M. The state of deep, dreamless sleep — no experience, no objects, no self. Yet you wake refreshed. Something sustained you in the absence of all content. That something is Prajna — the intelligence that holds experience together.
Turiya — The Fourth. The silence after Om. Not a state among states but the ground of all states. Not experienced as an object but recognised as the subject of all experience. The texts say it is not inward, not outward, not between, not a mass of consciousness, not conscious, not unconscious. It is unseen, beyond ordinary transaction, ungraspable, without distinguishing marks, unthinkable, indescribable.
This self is Brahman. This self has four quarters — waking, dreaming, deep sleep, and the fourth. The fourth is Turiya. This is the self. This is Brahman. This is what should be known.
The Mandukya does not give you a practice. It gives you a map. And then it invites you to notice: you have been in all four states. Something was present in all of them — something that witnessed waking, witnessed dreaming, and registered even the blankness of deep sleep.
That something is what you are. Not a state. The witness of all states. Find that, the Upanishad says, and you have found everything.