The Aitareya Upanishad is a very short sequence of five stanzas set in the Aitareya Aranyaka segment of the Rig Veda. It is attributed to the seer Mahadasa Aitareya, so called for being born to Itara, and by reason of her lower caste,not being considered a twice-born. When for this reason the child was denied a seat on his father's lap at a sacrificial ceremony, Itara prayed in distress, to the Goddess Earth. Responding to Itara's prayer, the goddess imparted knowledge to Aitareya, from which Aitareya proclaimed the Upanishad that goes by his name. The story carries a strong Vedic affirmation of the truth that man-made social differences have only limited social purposes, but have no place in the spiritual plane, where one Ultimate Truth alone prevails.
The Upanishad, within its short span provides a panoramic view of the process by which, Brahman, that one Ultimate Unitary Consciousness manifests itself into that differentiated totality that we cognize as existence. This process of creation is described in terms of an act of a Conscious Will which sets into motion the process of evolution starting with the macrocosm and going down to the last detail of the microcosm, all within a structured framework of space and time.
From the Ultimate Consciousness emerged energy, a gross form that aggregated into matter in all its forms and states to create the world of physical existence ( indeed what modern Physics says); and a subtle form that entered the human form and imparted activity, movement and life (the unique contribution of ancient Indian Metaphysics). Entry of this life-giving Prana through the feet is an appropriate allegory to represent the imparting the capacity for movement, which distinguishes man from the static world of plants.
The lighting up of man's inner Self by that Ultimate Consciousness, represents the final step in the evolution of man, that invests him with consciousness or awareness, not only of the external world around him, to serve life's transient purposes,but also of that eternal Ultimate Consciousness from which he and everything around him have originated. The entry of this consciousness into man's being through the top of the skull, allegorically and appropriately refers to its seat in the brain, which we cognize to be the seat of consciousness.