Tao Te Ching 59

For regulating the human in our constitution and rendering the proper service to the heavenly, there is nothing like moderation.  

It is only by this moderation that there is effected an early return to man's normal state. That early return is what I call the repeated accumulation of the attributes of the Tao. 

With that repeated accumulation of those attributes, there comes the subjugation of every obstacle to such return. Of this subjugation we know not what shall be the limit; and when one knows not what the limit shall be, he may be the ruler of a state.  

He who possesses the mother of the state may continue long. His case is like that of the plant of which we say that its roots are deep and its flower stalks firm: this is the way to secure that its enduring life shall long be seen.