Sri Aurobindo translates Aitareya Upanishad, Chapter 1, Section 1: “Hari OM. In the beginning the Spirit was One and all this (universe) was the Spirit; there was nought else that saw (Or, moving). The Spirit thought, ‘Lo, I will make me worlds from out my being.’ These were the worlds he made: ambhah, of the ethereal waters, maricih, of light, mara, of death and mortal things, apah, of the lower waters. Beyond the shining firmament are the ethereal waters and the firmament is their base and resting-place; Space is the world of light; the earth is the world mortal; and below the earth are the lower waters. The Spirit thought, ‘Lo, these are the worlds; and now will I make me guardians for my worlds.’ Therefore he gathered the Purusha out of the waters and gave Him shape and substance. Yea, the Spirit brooded over Him and of Him thus brooded over the mouth broke forth, as when an egg is hatched and breaketh; from the mouth brake Speech and of Speech fire was born. The nostrils brake forth and from the nostrils Breath and of Breath air was born. The eyes brake forth and from the eyes Sight and of Sight the Sun was born. The ears brake forth and from the ears Hearing and of Hearing the regions were born. The Skin brake forth and from the Skin hairs and from the hairs herbs of healing and all trees and plants were born. The heart brake forth and from the heart Mind and of Mind the moon was born. The navel brake forth and from the navel apana and of apana Death was born. The organ of pleasure brake forth and from the organ seed and of seed the waters were born.”
The Upanishad declares that there is One Spirit which constitutes the manifested universe out of its own being. There is no separate creator God who fashions worlds that are separate from himself. In the Life Divine, Sri Aurobindo translates a famous passage from the Rig Veda on the same theme, which helps illuminate the subject: “Then existence was not nor non-existence, the mid-world was not nor the Ether nor what is beyond. What covered all? where was it? in whose refuge? what was that ocean dense and deep? Death was not nor immortality nor the knowledge of day and night. That One lived without breath by his self-law, there was nothing else nor aught beyond it. In the beginning Darkness was hidden by darkness, all this was an ocean of inconscience. When universal being was concealed by fragmentation, then by the greatness of its energy That One was born. That moved at first as desire within, which was the primal seed of mind.” (Rig Veda X.129, cited in The Life Divine, pg. 240)
It is difficult to grasp the concepts of a timeless, infinite Existent creating a universe of limited functionality of time and space. The transient universe is not different from the timeless Being; rather it creates the sense of fragmentation and separation, and the systematic rolling out of its qualities and nature through a process we perceive as Time. In trying to describe this process, the Upanishadic seer has to use human language with all its limitations. One thing to be noted here is that the sense-organs were developed prior to the objects of these senses. This is an attempt to reverse our normal way of seeing and understanding with the mind which would place the object’s existence first, and then create the organs to perceive them. Any attempt to apply mental logic to something beyond the mind’s ability to grasp is clearly subject to failure. Meditation and contemplation on the sense behind the words is the only way to unravel these mysteries at all.
Sri Aurobindo, The Upanishads, Aitareya Upanishad, pp.285-294