Birth of Human Being:
Initially it (the human being) remains in first womb that is the body of man. What is known as Seminal fluid emanates as the essence of his physical body including limbs and organs. The man nurtures this essence of his being in his body first.
The conception of human form takes place when the man implants his seed in a woman and his semen joins the ovum to set in motion the process of embryonic growth.
This is the first birth.
The semen is accepted by woman’s body as her own part, so it does not hurt her or gets rejected. She nurtures the soul of being in her uterus.
The woman who holds the soul in her womb is to be nurtured and nourished.
While the child is growing in the womb, he is taught about life by his father. He also performs ceremonies for the child’s coming into existence after he gets delivered from mother’s womb. And in this way he celebrates his own perpetuation though progeny. This is the way Life propagates.
This is the second birth
The son establishes himself in place of his father as his representative in the world to perform meritorious deeds. With the passage of time, he feels fulfilled with a life well spent. Gradually his body grows old and gets discarded. He departs from the material world to be born in another life.
This is the third birth.
This way the Human Being, riding on three consequent phases of life moves through the ocean of material world. At any moment of this endless cycle he can experience the Atman as propounded by the scriptures, and become free from the bondage.
Just like Rishi Vamadev stated that he came to realize the Ultimate Reality while he was in his mother’s womb. He says that prior to this experience; he was caught up in iron shackles of series of births and deaths.
With the awakening of Truth within him he penetrated the shell of this prison like a sharp eyed falcon. Having realized his True stature, he transcended the world that is perceived by sense organs after his death and having all his desires fulfilled in that heaven, became immortal.
(a continued translation of Aitareya Upanishad)