The Aitareya Upanishad is an older Upanishad and covers several subject areas. It has 3 chapters. The first deals with the process of creation of the universal manifestation. The second deals with the 3 births of the Atman. The third deals with the nature of Spirit, the processes that revolve around the creation of food (matter) and the action of desire in the processes that move the manifestation forward.
It is difficult to try and understand this Upanishad using systematic mental logic based on our scientific understanding of the world. It must be remembered that the Upanishads in general look upon the world of Matter as the end process of an involution of consciousness from its transcendent and universal status to one of being condensed down into a material form; and that therefore, they follow more the image of the tree with its roots above, as found in other Upanishads, rather than the more Western view that starts from Matter and tries to develop conscious existence as something that is created from Matter without any prior consciousness involved.
We can then turn to the Western religious viewpoint and see that both the Old Testament and the New Testament discuss Creation. In Genesis, the Creator God is external to the creation. Yet we see that he first creates the form, then breathes life into it, and later it acquires conscious awareness. The New Testament adds that “In the beginning was the Word. And the Word was with God and the Word was God.” This is a more metaphysical view of creation that tries to address the issues raised by the creation story told in the Old Testament.
The Aitareya Upanishad addresses the issue of Creation from the standpoint that it is not a “separate” creation, but is created by itself, within itself, out of its own substance, and that substance is Brahman, the all-encompassing Existence-Consciousness-Bliss. As the Taittiriya Upanishad states, there is One Spirit and there is no other.
The Aitareya Upanishad is not attempting to be some kind of scientific treatise on the mechanisms of creation. It is rather focused on the big picture of “how creation comes about” and how the seeker can achieve liberation through Oneness with the Spirit by overcoming the force of desire that moves the action in the world.
Some of the language and turns of phrase are foreign to us and archaic in nature, thus making this ancient scriptural text somewhat difficult for us to appreciate in its fullness. We shall attempt to focus on the “big picture” issues as we proceed through the Aitareya Upanishad rather than bog down in an attempt to interpret each nuance that arises from the attempt to translate ancient conceptions and insights into modern language through multiple languages.
As with all the Upanishads, these were not intended to be comprehensive, systematic expositions but as part of an interaction between the teacher and the student that also involved clarifications, and “homework” by the student in the sense of meditation and contemplation on the issues, with follow up discussions or directions. They are intended to provide a direction, therefore, for concentration, rather than a set of finished, factual answers to be memorized by rote. If we expect a scientific exposition in the Western sense, we will never enter into the meaning intended by the sages of the Upanishads.
Sri Aurobindo, The Upanishads, Aitareya Upanishad, pp.285-294