Before the birth of all things, there existed an undifferentiated whole. A solitary void: unchanging, yet operating everywhere, without exhaustion. It is therefore considered the source of everything.
I do not know its true name, although some call it the Tao.
If compelled to characterize it, I would simply call it great. For to be great implies that it is far-reaching, to be far-reaching implies distance, and to be distant implies returning to the source.
Thus the Tao is great, Heaven is great, Earth is great, the wise person is also great.
In the universe there are four great ones, and the wise person is one of them. The wise person follows the laws of Earth, Earth follows the laws of Heaven, and Heaven follows the law of Tao.
The Tao, with nothing to follow, is natural unto itself.
(from Tao Te Ching, verse 25, translation by Robert Brookes)