Sri Aurobindo introduces the subject of rebirth with a few relevant quotations from the ancient texts of India, the Bhagavad Gita and the Swetaswatara Upanishad:
The Gita: “An end have these bodies of an embodied soul that is eternal;…it is not born nor dies nor is it that having been it will not be again. It is unborn, ancient, everlasting; it is not slain with the slaying of the body. As a man casts from him his worn-out garments and takes others that are new, so the embodied being casts off its bodies and joins itself to others that are new. Certain is the death of that which is born and certain is the birth of that which dies…” (Bhagavad Gita, Ch. II, 18, 20, 22, 27)
Swetaswatara Upanishad: “There is a birth and growth of the self. According to his actions the embodied being assumes forms successively in many places; many forms gross and subtle he assumes by force of his own qualities of nature…. (Swetaswatara Upanishad, V.11, 12)
When one reflects on the significance of life, it is the facts of birth and death which create the greatest issues: “Birth is the first spiritual mystery of the physical universe, death is the second which gives its double point of perplexity to the mystery of birth; for life, which would otherwise be a self-evident fact of existence, becomes itself a mystery by virtue of these two which seem to be its beginning and its end and yet in a thousand ways betray themselves as neither of these things, but rather intermediate stages in an occult processus of life.”
Sri Aurobindo, The Life Divine, Book 2, Part 2, Chapter 20, The Philosophy of Rebirth
