In the beginning was Self (Atman) alone, in the shape of a person. He, looking round, saw nothing but his Self. He first said, "This is I"; therefore he became "I" by name. Therefore even now, if a man is asked, he first says, "This is I," and then pronounces the other name which he may have. And because before all this he (the Self) burnt down all evils, therefore he was a person (purusha). Verily he who knows this burns down everyone who tries to be before him. He feared, and therefore anyone who is lonely fears. He thought, "As there is nothing but myself, why should I fear?" Then his fear passed away. For what should he have feared? Verily fear arises from a second only. But he felt no delight. Therefore a man who is lonely feels no delight. He wished for a second. He was as large as man and wife together. He then made this, his Self, to fall in two, (pat) [the word "pat" means two] and thence arose husband (pat) and wife (patni). Therefore Yagnavalkya said, "We two are thus (each of us) like half a shell." Therefore the void which was there is filled by the wife. He embraced her and men were born. She thought, "How can he embrace me afer having produced me from himself? I shall hide myself." She then became a cow, the other became a bull and ebraced her, and hence cows were born. The one became a mare, and the other a stallion, the one a male ass, and the other a female ass. He embraced her, and hence one-hoofed animals were born. The one became a she-goat the other a he-goat; the one became a ewe, the other a ram. He embraced her, and hence goats and sheep were born. And thus he created everything that exists in pairs, down to the ants.

Brihadaranyaka Upanishad. Translated by F. Max Müller