Tao Te Ching 56

He who knows the Tao does not care to speak about it; he who is ever ready to speak about it does not know it.

He who knows it will keep his mouth shut and close the portals of his nostrils. He will blunt his sharp points and unravel the complications of things; he will temper his brightness, and bring himself into agreement with the obscurity of others. This is called "the Mysterious Agreement."

Such a one cannot be treated familiarly or distantly; he is beyond all consideration of profit or injury, of nobility or meanness—he is the noblest man under heaven.