Aitareya is a matronymic or patronymic deriving from the SANSKRIT root itara. It means “son of itara” (either masculine or feminine), who would be his mother or father. This is an ancient RIG VEDIC sage who also goes by the name of Mahi-dasa. Credited to him are the Aitareya Brahmana, the Aitareya Aranyaka, and the Aitareya Upani-shad, all texts attached to the RIG VEDA. The Aita-reya Upanishad is found in the Aitareya Aranyaka, constituting chapters 4 to 6 of that work.
The Aitareya Upanishad begins with cosmo-logical verses showing how the ultimate being, the ATMAN or Self, created the worlds, the ele-ments, and human beings. Important here is the connection between each of the elements of the divine PURUSHA, which is the template Person, and the elements of nature aspects of the cosmos and the human being. From the original Person fire, air, Sun, the quarters of space, the Moon, death, and water emerge. All of these elements again go into making up the human being. Once this takes place the Self enters into the human being that has emerged as the result of his creation. This then makes clear that the self of a human being is the Ultimate Self, which is the source of everything.
Further reading: S. N. Dasgupta, A History of Indian Philosophy, Vol. 1 (Delhi: Motilal Banarsidass, 1975); Arthur B. Keith, The Aitareya Aranyaka (Oxford: Clarendon Press, 1909); Swami Nikhilananda, trans., The Upanishads, Vol. 3 (New York: Ramakrishna-Vive-kananda Center, 1975); S. Radhakrishnan, The Princi-pal Upanishads (Atlantic Highlands, N.J.: Humanities Press, 1994).
Encyclopedia of Hinduism. A. Jones and James D. Ryan. 2007.