The taittirIya Upanishad explains brahman as:
सत्यं ज्ञानमनन्तं ब्रह्म । — 2.1.1, taittirIya upa.
[Beingness, Knowingness and Infiniteness is brahman.]
Unending Beingness and Knowingness is the nature of brahman.
There are two endpoints for anything in this world — one is the beginning and the other is the ending. But brahman, The Knowingness, as the Upanishad says is Infinite, without limitations or edges or endpoints. It has neither a beginning (origination) nor an end (culmination).
From a common sense point of view, it may be argued that “Knowingness” cannot exist on Its own in the absence of a knower and something to be known. Can Knowingness ‘be’ in a vacuum? Is Its presence not dependent on a knower who would have been the locus for It? In the usual parlance, knowingness is that which interlinks the ‘knower’ with the ‘known.’ With the two end-members being absent, can ‘Knowingness’ exist on its own independent of the other two?
For example, let us take ‘hunger.’ There has to be someone who is hungry. Also there has to be a substance that can satiate the hunger. Suppose there is none who is hungry, nor anything edible in this world. Can the word ‘hunger’ mean anything under those circumstances? ‘Hunger’ cannot “be” on its own, nor could ‘experience,’ the feel of being hungry to eat something “be”; hunger cannot exist eating itself!
Similarly, for ‘fear’ to be present, there has to be someone who feels the fear, and something to cause the fear. In the absence of anything to be afraid of and someone who is scared, ‘fear’ does not have any meaning.
Extending the same logic, we may question if Knowingness can be present in the absence of the knower (the knowing person, me) and the known (the world, the object). Does not Knowingness establish a relationship between the knower and the known? There is no scope for a ‘relation’ to exist all alone by itself, when there are no ‘relata’ to be related to one another by it.
Counterintuitively for us, the amazing answer the aitareya Upanishad provides is that neither the individual nor the world exist and what is really present is Knowingness alone! It asserts that the jIva and jagat (the individual and the world) depend on Knowingness and not the other way round. It makes the significant declaration, a mahA vAkya:
प्रज्ञानं ब्रह्म ॥ — 3.5.3, aitareya upa.
[The Absolute Knowingness is brahman.]
prajnAna is derived as: prakRiShTam jnAnam prajnAnam, meaning that the Knowingness referred to here is prakRiShTam. ‘prakRiShTa’ stands for exceptional, extraordinary, magnificent, distinguished etc.
Thus the Knowingness that the Upanishads talk about is significantly different from the ordinary ‘knowingness’ we possess in our day to world – like, for example, London is the Capital for England; The Sun raises in the East; Dr. Einstein was a theoretical Physicist; I have to take the 8:30 flight tomorrow; and so on. These are all ‘memory-based’ informations, commonly covered as knowledge. One can become an “expert” accumulating more and more of such knowledge stored in his mind on any subject. The accumulated knowledge and expertise ends with him. This knowledge is ever growing and ever incomplete and imperfect. The Vedantic Knowingness, in contrast, is eternal, ever Perfect and Complete, always New and not stored in the mind (memory system).
And Shankara tells that mokSha (Liberation) is brahman Itself:
ब्रह्मभावश्च मोक्षः । — Shankara at 1.1.4, BSB.
[Liberation is the state of identity with brahman (Translation: Swami Gambhirananda).]
Therefore, Liberation is nothing but being brahman or in other words, being as the endless Knowingness, the endpoints being the knower and the known, aka, the jIva and the jagat. All the three – jIva-jagat-Ishwara – dissolve in the Perfection of the Absolute Knowingness like the rivers merging with the Ocean and, once merged they cannot retain their presence and identities (perhaps beyond a short while, as chAndogya 6.14.2 says).
[Note: The Sanskrit word “jnAnam” occurring in the 2.1.1, taittirIya is usually translated as “Knowledge” or higher Knowledge or Awareness etc. I preferred to translate it as “Knowingness” because the English word ‘knowledge’ is a broad term that connotes “the understanding gained through experience or study.” It encompasses a bundle of “the facts, feelings or experiences known by a person or group of people,” or it refers to “the state of knowing.” Such a translation often is quite confusing because, “jnAna” in its Vedanta sense does not refer to the accumulated data or mass of information stored but to that elemental quality or ability “to know, to sense or detect” like in a sensor. I hope the word “Knowingness” can bring out better this subtle difference leading to a correct understanding because understanding the word “jnAna” is very crucial in and fundamental to Advaita doctrine, as the essay explained above.]