Mahaa Vakya in Vedanta philosophy is a core sentence or a theme statement in a few words, which can be expounded in a book of thousands of pages. So concentrated is the message in a Mahaa vaakya. Swami Dayananda Saraswati in this book explains in very simple but focused words the meaning of the Mahaa Vaakya "Tatvamasi: Tat Tvam Asi" meaning, You are that. This sentence can be taken as an answer to the self interrogation "Who Am I" which a spiritual student has to ask himself when traveling on the path od self realization. This is a condensation published by Tattvaloka magazine of Shringeri Mutth. Source of Original book is also mentioned.