Aitareya, also known as Mahidāsa Aitareya, is the ṛṣi (sage) credited with the authorship of the Brāhmaṇa, Āraṇyaka and Upaniṣad (of the Ṛgveda) that go in his name. The Chāndogya Upaniṣad (3.16.7) mentions him as having lived for 116 years as a result of meditating upon his life as a yajña or sacrifice. This has become known as ‘puruṣayajña.’
According to other accounts given in the purāṇas, he was the son of Itarā and Māṇḍuki (whence his name Aitareya). Since he never spoke, the mother Itarā, thinking that he was dumb, prayed to Mahī (mother Earth) who blessed him with divine knowledge and wisdom (whence the additional appellation Mahīdāsa or Mahidāsa).
He was an ardent devotee of Lord Vāsudeva and had been repeating constantly the dvādaśākṣarī mantra (the twelve-lettered mantra, viz., ‘Oṁ namo bhagavate Vāsudevāya’). Once the Deity appeared to him in a vision and comman-ded him to take to the second stage of life, that of the householder, to please his parents. Accordingly he went to one Harimedhas who was performing a sacrifice, exhibited his divine powers and knowledge and secured the hand of his daughter in marriage as also enough wealth.
The Vedic sections associated with his name are said to have been revealed to him in the yajñaśālā (sacrificial shed) of Harimedhas.