天下有始，以为天下母。既得其母，以知其子，既知其子，复守其母，没身不殆。塞其兑，闭其门，终身不勤。开其兑，济其事，终身不救。见小曰明，守柔曰强。用其光，复归其明，无遗身殃；是为习常。
(The Tao) which originated all under the sky is to be considered as the mother of them all. When the mother is found, we know what her children should be. When one knows that he is his mother's child, and proceeds to guard (the qualities of) the mother that belong to him, to the end of his life he will be free from all peril. Let him keep his mouth closed, and shut up the portals (of his nostrils), and all his life he will be exempt from laborious exertion. Let him keep his mouth open, and (spend his breath) in the promotion of his affairs, and all his life there will be no safety for him. The perception of what is small is (the secret of clear-sightedness; the guarding of what is soft and tender is (the secret of) strength. Who uses well his light, Reverting to its (source so) bright, Will from his body ward all blight, And hides the unchanging from men's sight.