The Upanishads specially Mandukya has talked about the Turiya or the Fourth: The one (I) that manifests itself across the three states of Wakefulness (I am watching a movie), Dream (I am dreaming (seeing) that I am watching a movie and Deep Sleep ((After I wake up, I recall that I was sleeping)). Examples have been given by the ancient scholars as to how the I, the Consciousness, witnesses the waker, the dreamer and the deep sleeper. It has also been stated pretty vividly as to how and why the body-mind (i) can only experience or realize(real eyes) the Witness-Consciousness (I) through and across the three states of the conscious (wakefulness), subconscious(dream) and the unconscious (deep sleep) and can never be seeked independently of these states of being. The Witness-Consciousness (I or Ātman) upon realizing Itself (Paramātman) gets itself merged into the ultimate Truth (Brahman).

It is to be noted here that just as the Ātman is experienced across the three stages of Wakefulness, Dream and Deep Sleep, the Brahman also is defined as the Trinity of Existence-Consciousness-Bliss(Sat-chit-ananda) in the Upanishads.

The Existence of the Brahman is the material universe. The universe of the body-mind. The very coordinates of which lay in the space-time-object aspect.

The space is the limitless or eternal(having neither a beginning nor an end) spread that pervades all that is of a tactile or tangible nature. For example in your bedroom you have a bed, a small table and an almirah. The space which pervades through and across the bedroom (ceiling, floor, walls), the table and the almirah. The space pervades all other rooms and their respective contents. The space pervades your garden and your house and it pervades you(your body-mind entity).

The time aspect of the Existence(of the Brahman) pervades all that's of a transitory nature. Your bedroom was once built and it didn't exist before that. Also, it is going to cease to exist at one point of time(in the future). The contents of the bedroom as well. The wooden table for example was made by a carpenter and wasn't there before that. It is not going to be there forever as well. You yourself were born once and shall die sometime in the future but are limited in time. However, the Time of the Brahman is the time in its eternity that was, is and shall stay independent of all these starts and stops that time means to us in our daily lives. The Time of the Brahman is the time of the time that we follow or understand as the quotidian. The time that was there when you weren't born in this body-mind, The time that was there when you were born, The time that was there when you got your house built and shall be there when you shall be no more in this body-mind.

The object aspect of the Existence(of the Brahman) is the fact that every object is unique and that no object can be reduced to nothing. Every object was, is and shall be independent of the change that it undergoes. The object of the Brahman is the very existence of different objects which is eternal. Your bedroom might cease to exist as a bedroom but then its very existence is going to be in some other form. The wooden table of your bedroom is different from your bedroom. The table shall undergo some damage or change but continue to exist in whatever form that might be. You, even before you were born, were in other bodies in different forms of sperms and ova and more, are now in your body-mind and shall be ash and dust when you die. The ash and dust shall continue to exist in whatever form that might be.

The Consciousness(Witness) aspect of the Brahman can be understood by the principle of the Seer-Seen Discrimination. Let's take the example of the bedroom. When you see your bedroom. Your eyes are the seer and the bedroom is the seen(scene). Now, from this example we understand that the Seer and the Seen are different. Here the word Seer is used metaphorically and it means Witness. The Seen is the Witnessed. So, your eyes are the witness of the bedroom (Witnessed). Now are your eyes witnessed too? If yes, then by whom or what? Yes, we do understand that you are already aware of your eyes. Though you can't see them yourself(unless of course you stand in front of a mirror) you are aware of your eyes because of the fact that you can see the bedroom(Witnessed—if something is witnessed then there must be a witness witnessing the witnessed) and also because your mind witnesses your eyes. Your mind is aware of your eyes(if you can clearly see the bedroom or not or if you need your spects). Now the mind is the witness of your eyes(the witnessed). Your mind and your eyes are different and your mind is the Seer. Your eyes are the Seen. Can your mind be witnessed too? The answer is simple. It is yes. You know you have a mind. Just the very fact that this question appears somewhere within us proves the fact that the mind too is witnessed. Thoughts appearing in the mind and you are aware of those thoughts. The mind is witnessed. But by whom? The moment a thought appears in the realm of the mind. It is known to us. The witness here being the intellect. The intellect is the witness and the mind, the witnessed. The Seer is the intellect and the Seen, the mind. Are we aware of the intellect? Generally speaking, we should be since we know for sure that the moment a thought appears in the mind it is often analyzed and seen through. For example, the simple idea of the fact that the thought appearing in the mind is a good or bad one. Or the fact that a thought in the mind makes us uncomfortable or happy or sad. In short, the intellect has a witness that makes us aware of the intellect. The Seer witness witnesses the Seen intellect. The witness or the Seer here is the cause and we are already aware of it simply because we are aware of the witnessed or the Seen intellect. But the question is who or what makes us aware of this cause. Well, we know that there is bound to be a Seer here as well. It has already been proved that if there is a Seen, there has to be a Seer. Now, before going any further we need to recapitulate the Seer-Seen progression this far. First of all, the bedroom was the Seen and the eyes were the Seer. Then the eyes became the Seen and the mind became the Seer. Then the mind became the Seen and the intellect became the Seer. By now, we have one Seer and it's the intellect and we have three Seens: bedroom, eyes and mind. Let's continue, the intellect now gives way to the cause which is the new Seer and the intellect joins the list of the Seen. And finally, or if I can use this expression in an experience as eternal as this, the cause gives way to the new Seer which is the Consciousness and the cause becomes a Seen. We have one Seer and it is the (Witness)Consciousness and we have five Seens: bedroom, eyes, mind, intellect and cause. The Witness-Consciousness is not subject to the Seen experience. Becoming aware of it is a condition of the eternity from where there's no coming back. Hypothetically speaking, if the Witness-Consciousness is touched by me then I become it and there is no Seer left to do any more witnessing. So ideally it is like if you touch the Witness-Consciousness then you aren't anymore left to witness the Consciousness as a different entity and you become eternity yourself.

Before getting on with the understanding of the Bliss part of the Upanishad's definition of the Brahman, we need to reconsider the definition of the Brahman as it is there in the Upanishad: Existence-Consciousness-Bliss. Here, the Brahman is referred to as the Truth(sat) Consciousness(chit) Bliss(ananda). Now what is the exact relationship between these three notions Existence(Truth)-Consciousness-Bliss?

The answer to this question can be found in the very analysis of the Existence-Consciousness of the Brahman. When we delved into the space-time-object aspect of the Existence of the Brahman we found in each of those three aspects a sense of eternity. The space of the Existence of the Brahman is the all-pervading space that has no limits whatsoever. It is through and across every tangibility that was, is and shall be. The time of the Existence of the Brahman is the continuum that permeates the transitory thereby transcending it. The object of the Existence of the Brahman is the eternal that in spite of any death and destruction and transformation continues to be as it used to and shall be. The Consciousness of the Brahman is the eternal Seer(which if witnessed makes of the witness eternity or Consciousness itself) that witnesses the Existence of the Brahman through the spectrum of the space-time-object. The space-time object, epitomizing the eternal Existence of the Brahman, can only shine in the eternity of the Consciousness in the Consciousness itself. Thus, we can hereby conclude that in the definition of the Brahman, Existence-Consciousness-Bliss, the relationship between Existence and Consciousness is "eternity".

Eternity, the nuclear property of the Existence-Consciousness compound, is the quintessence of Bliss (Literally - Joy; literally - Solitude) which is manifested across the ever-growing ultimate called Brahman.

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