MANTRA – 12
amatrash  chaturtho.   Avyavaharyah    prapanchopashamah  shivo. advaita  evam  onkara  atmaiva   samvishaty  Atmana.a.Atmanam  ya   evam  veda .. 12.. 
That  which has no parts (soundless), incomprehensible (with the aid of sense  organs), the cessation of all phenomena, all bliss and non-dual AUM, is the  fourth and verily the same as Atman. He who knows this merges his self  into the Cosmic Self. (He never again feels he is an individual self).
There  are no more quarters. When you go beyond the three quarters, the three states  of A, U, and M, then you reach chaturtha, the fourth one, turiya.  This state is pure consciousness, beyond Isvara. The gross universe is then  gone. The dream universe is gone. All universes, all diversities, all  dualities, are gone. You are in the state of suddha chaitanya – turiya and there is only your Self, Atman. You are liberated and there is no  birth for you.
Prapancha – The five elements represented by the phenomenal world,  this diversity. When you attain turiya, then so far you are concerned  this phenomenal world is only an illusion. It comes to an end for all practical  purposes (upasama). There is no more world for you. You see only Brahman  and nothing else. Then there is only Siva, only joy, only good. And there is advaita,  no diversity. There is only unity. You see yourself everywhere, in every being  – one and the same self everywhere. You realize that this AUM is nothing but  the Self, the Atman – evam omkara atmaiva.
He who  knows this Truth attains real knowledge, transcendental knowledge. He knows  that he alone exists – the entire universe getting merged in him. That is the  final state. You don’t see anything outside. Everything is within.
Samavisat – he merges entirely. You merge entirely into your Self.  You withdraw into yourself because to you this world has no separate existence. Atmana Atmanam – the self into the Self. The individual self merges into  the Cosmic Self. The jivAtman and the paramAtman become one.
iti  mandukyopanishat.h samapta 
  HERE  ENDS THE MANDUKYA UPANISHAD.
A  bird’s eye view of Gaudapada’s karikas is given in the Annexure (see  next chapter).