Sri Aurobindo translates Aitareya Upanishad, Chapter 2: “In the male first the unborn child becometh. This which is seed is the force and heat of him that from all parts of the creature draweth together for becoming; therefore he beareth himself in himself, and when he casteth it into the woman, ’tis himself he begetteth. And this is the first birth of the Spirit. It becometh one self with the woman, therefore it doeth her no hurt and she cherisheth this self of her husband that hath got into her womb. She the cherisher must be cherished. So the woman beareth the unborn child and the man cherisheth the boy even from the beginning ere it is born. And whereas he cherisheth the boy ere it is born, ’tis verily himself that he cherisheth for the continuance of these worlds and their peoples; for ’tis even thus the thread of these worlds spinneth on unbroken. And this is the second birth of the Spirit. Lo, this is the spirit and self of him and he maketh it his vicegerent for the works of righteousness. Now this his other self when it hath done the works it came to do and hath reached its age, lo! it goeth hence, and even as it departeth, it is born again. And this is the third birth of the Spirit. Therefore it was said by the sage Vamadeva, ‘I, Vamadeva, being yet in the womb, knew all the births of these gods and their causes. In a hundred cities of iron they held me down and kept me; I broke through them all with might (Or, speed) and violence, like a hawk I soared up into my heavens. While yet he lay int he womb, thus said Vamadeva. And because he knew this, therefore when the strings of the body were snapped asunder, lo, he soared forth into yonder world of Paradise and there having possessed all desires, put death behind him, yea, he put death behind him.”
This chapter focuses on the continuity of the manifested universe through the processes of birth and death. Hunger and the force of desire were previously identified as a mechanism for development. There needed still to be a mechanism for consciousness to systematically grow and this then led to the question of rebirth.
It must be noted that the sages clearly understood the concept behind the modern science of genetics. They identified the first birth as the gathering of the essential elements of the father and the creation of the seed that transmitted this into the mother’s womb. The mother incorporated this seed into her own being, representing the mother’s contribution to the child’s birth. This was the second birth. Along the way, the sages recognised the importance of pre-natal care, the “cherishing” of the mother during the course of the pregnancy. Reference is then made to the death and rebirth of the individual, which is the third birth of the Spirit. This provides for the continuity and development of the world.
The question of liberation of the soul from birth and death and the bonds of desire is next taken up in the final two verses which describe the sage Vamadeva. It is implied that a realised soul can actually take up residence in the foetus and be born with full knowledge and awareness. This is a further implication of rebirth. While not every soul may take up residence at this stage, a realised soul may choose to do so. Recognising the mechanism of birth and death, the action of desire and the bonds of attachment to the senses and their objects, the sage overcame desire and achieved liberation.
Sri Aurobindo, The Upanishads, Aitareya Upanishad, pp.285-294