(I received a few queries regarding Mahavakhya, of which I made a reference in my blog "I AM THAT I AM" So by way of explanation I am publishing here my article that appeared in Medha, the annual magazine of school of Vedic Sciences, Sydney)
1) Prajnanam Brahma –“Consciousness is Brahman”. This occurs in Aitareya Upanishad of Rig Veda
2) Aham Brahma Asmi – “I am Brahman”. This occurs in Brihadharanyaka Upanishad of Yajur Veda
3) Tat Tvam Asi – “That thou Are”. This occurs in Chandogya Upanishad of Sama Veda.
4) Ayam Athma Brahma – “This Self is Brahman”. This occurs in Mandukya Upanishad of Atharvana Veda.
Mahavakhya removes the misconception that Self is different from Brahman. As Brahman is the source of security, peace and happiness, bhedha buddhi makes one run after these searching them elsewhere and Ikya Buddhi i.e. knowledge of identity, makes one realize them within oneself. Abiding in this knowledge of Jiva Brahma Ikyam at all times, gives one Jivan Mukthi, i.e. Moksha, while living. In that sense mahavakhya gives one, liberating Self Knowledge. But we should always remember that when Self is equated with Brahman it is like equating water in the ocean with water in a container in the seashore on the basis that both have the same chemical formula H2O or like equating tiny waves in the ocean with the mighty ocean itself on the basis that both are essentially water only. It is not the individual with the upadhi of sareera triam, equated with the Brahman with the upadhi of prapancha triam. We shall see this briefly taking one of the mahavakhyas for analysis, namely the updesa vakhya.
“Tat Tvam Asi” occurs in Chapter 6 of Chandogya Upanishad, where Guru Uddalaka instructs sishya Svetaketu through examples the nature of Brahman. The importance of this upadesa vakhya can be seen from the fact that it is repeated nine times in the course of the teaching. This statement is in the form of an equation Tat=Tvam. Equating both sides is not necessary if they are same like, 5 and 5. Again equating both sides is not possible when they are different like, 5 and 8. Equating becomes necessary, only if they appear to be different but, on analysis, they reveal identity like, 5+1 & 8-2. That is what happens in this equation Tat=Tvam, when you take the lakshyartha for Tat and Tvam, instead of the vachyartha.
Vachyartha, which is also called mukhya artha, is the primary meaning and lakshyartha is the secondary meaning. When I say I bought a banana, it means I bought the whole fruit. But when I say I ate a banana, it refers only to the pulp portion and not to the whole fruit with the skin. In the first instance, we have taken the primary (literal) meaning, vachyartha, for banana i.e. the whole fruit with skin. In the second instance we have taken the secondary (contextual) meaning, lakshyartha, for banana i.e. the edible portion without the inedible skin. For getting the lakshyartha in the place of vachyartha, we employ one of the three following methods:
1) Jahallakshana – Taking the secondary meaning, excluding the primary meaning. For example when you order takeaway coffee, and you are asked ‘any sugar’ and you reply ‘two spoons’, coffee is given not with two spoons, but with two spoonful sugar mixed.
2) Ajahallakshana – Taking the secondary meaning, without sacrificing the primary meaning. For example when you order coffee, it is served in a cup which you have not ordered but understood.
3) Jahadajahallakshana or Bhagatyagalakshana - Retaining certain portion of the primary meaning i.e. primary meaning is partially included and partially excluded as in the case of eating a banana, where only pulp portion is included and the skin portion excluded, while understanding the statement.
We are employing one of the three methods regularly for finding lakshyartha, when the vachyartha does not fit in. Only we are doing it automatically, without our being even aware of it. In the case of the statement, Tat Tvam Asi, when we take the vachyartha of both, we cannot equate the Jiva who is mortal and has all types of limitations and Brahman who is eternal and transcends all limitations. So we go to the lakshyartha of both on the basis of sastras, which is the pramanam for all matters concerning Self and Brahman, that cannot be objectified or conceptualized. Employing bhagatyagalakshana method and taking out the unequal upadhis ie sareera triam in Jiva and prapancha triam in Brahman we are left with Consciousness on both sides of the equation and that is identical. The same is done in anubhuthi vakhya, Aham Brahma Asmi, understanding Aham as standing for the Self , which is consciousness and not as referring to the individual as such with the body mind complex. The other two mahavakhyas, Prajnanam Brahma and Ayam Athma Brahma are much more straightforward as Consciousness is Athma, as per sastras.