This vast universe is a wheel. Upon it are all creatures that are subject to birth, death and rebirth. Round and round it turns, and never stops. It is the wheel of Brahman. As long as the individual self thinks it is separate from Brahman, it revolves upon the wheel in bondage to the laws of birth, death and rebirth. But when through the grace of Brahman it realises its identity with him, it revolves upon the wheel no longer. It achieves immortality.
Svetasvatara Upanishad. (This is the first time in Hindu literature that the image of the wheel is applied birth, death and rebirth.)