There are many upanishadic statements.
I want to know why these four only are considered mahavakyas?
- Prajnanam Brahma (प्रज्ञानम् ब्रह्म)
- Aham Brahma Asmi (अहम् ब्रह्म अस्मि)
- Tat Tvam Asi (तत् त्वम् असि)
- Ayam Atma Brahma (अयम् आत्मा ब्रह्म)
Which other schools consider them as mahavakyas?
Are there any Upanishad statements which indicate duality and thus they can be made mahavakyas? I know one. For eg: brahmaiva san, brahmapyeti "Becoming brahman, one enters brahman".(Brh. Ar: 4.4.6). This indicates two even after liberation, since author of action must be different from object.
A non advaitin can choose this as a mahavakya and interpret advaitic mahavakyas differently.
Why not this be a mahavakya?
The full verse translation from here is:
And here there is this verse: "To whatever object a man's own mind is attacbed, to that he goes strenuously together with his deed; and having obtained the end (the last results) of whatever deed he does here on earth, he returns again from that world (which is the temporary reward of his deed) to this world of action." 'So much for the man who desires. But as to the man who does not desire, who, not desiring, freed from desires, is satisfied in his desires, or desires the Self only, his vital spirits do not depart elsewhere,- being Brahman, he goes to Brahman
In any case, I am more looking towards logical explanation of why these four are chosen? Who is the first advaitin to say these four as mahavakyas, which means when did they enter into advaitin books for the first time and how did he justify choosing these four over other statements?