तत् त्वम् असि | tat tvam asi

“Tat tvam asi” means “That art thou.” It is found in the Upanishads, and refers to our experience of “identity” with Brahman. We see Brahman in all things, and the basis for our love of others is that they also are one with Brahman. Vivekananda spoke of the need for a “Practical Vedanta."This was using the principles of advaita in a practical way to achieve moral results. This was the basis of the Ramakrishna Mission which he founded. In support of this Practical Vedanta, Vivekananda referred to the mahavakya (great saying) tat tvam asi in the Upanishads. If we are identical with the other and with Brahman, then we will want to do good to the other. This mahavakya is therefore the foundation for morality. It is not that we do good to our neighbour out of altruism, but because the neighbour is identical to our self.

Some Indologists have said that the use of “tat tvam asi” in ethics is only relatively recent within Hinduism, and that in fact neo-Hinduism was influenced by Western interpretations of itself in coming to this viewpoint. Paul Hacker said that traditional Hinduism did not relate “tat tvam asi” to ethics. Hacker points to the German philosopher Schopenhauer, and to Schopenhauer’s student, Paul Deussen for this usage. Because of Schopenhauer’s world-denying philosophy, he himself did not advocate this morality. Deussen took the principle further and actually advocated it as the basis for how we should act. Deussen gave a lecture in Bombay on February 25, 1893 concerning the tat tvam asi theory of the foundation of ethics. He went again to India in 1896 and there met Vivekananda. Hacker says it is not until after this meeting that Vivekananda’s writings included the principle as a basis for ethics. Prior to this time, Vivekananda’s ethics were based on the idea of disinterested action. In fact, in his book Karma-Yoga Vivekananda said that it was foolish talk to speak of doing good to the world.

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