Aitareya Upanishad

"The Aitareya Upanishad belongs to the Aitareya Aranyaka and is a part of the Rig-Veda. Consisting of three parts, the Upanishad proper begins with the fourth section of the second part of the Aranyaka and comprises sections four, five, and six. The preceding part of the Aranyaka prescribes rituals for the attainment of oneness with Prana, or Saguna Brahman. According to some, the attainment of this oneness through rituals and meditation is the goal of human endeavour and the ultimate teaching of the Vedas. Shankaracharya, however, refutes this view and asserts that Self-Knowledge is the goal. This Knowledge is taught in the Aitareya Upanishad.

The Upanishad is divided into three parts. The method by which Self-Knowledge is taught is twofold. First is shown the illusory superimposition of names and forms (adhyaropa) upon Brahman, or Atman, and next, through their refutation (apavada), is revealed the sole reality of Atman. The verses up to the first sentence of I. ii. 13. deal with illusory superimposition, and then follows the refutation."

- Swami Nikhilananda