Khandogya-Upanishad: Third Prapathaka, Nineteenth Khanda
1. Aditya (the sun) is Brahman, this is the doctrine, and this is the fuller account of it:—
In the beginning this was non-existent. It became existent, it grew. It turned into an egg. The egg lay for the time of a year. The egg broke open. The two halves were one of silver, the other of gold.
2. The silver one became this earth, the golden one the sky, the thick membrane (of the white) the mountains, the thin membrane (of the yoke) the mist with the clouds, the small veins the rivers, the fluid the sea.
3. And what was born from it that was Aditya, the sun. When he was born shouts of hurrah arose, and all beings arose, and all things which they desired. Therefore whenever the sun rises and sets, shouts of hurrah arise, and all beings arise, and all things which they desire.
4. If any one knowing this meditates on the sun as Brahman, pleasant shouts will approach him and will continue, yea, they will continue.