Aitareya Upanishad, like other Upanishads of Hinduism, asserts the existence of Consciousness as Atman, the Self or Brahman. It contains one of the most famous expressions of the Vedanta, "Prajnanam Brahma" (Knowledge is Brahman/god/divine/holy),Commentary on Aitareya Upanishad Adi Shankara, pages 3–4 which is one of the Mahāvākyas.
