...and talkers do not know.
Saying attributed to the semi-legendary Chinese sage Lao tzu. This is actually the beginning line of a longer poem:
One who knows does not speak; one who speaks does not know.
Block the openings;
Shut the doors.
Blunt the sharpness;
Untangle the knots;
Soften the glare
Let your wheels move only along old ruts.
This is known as mysterious sameness.
Hence you cannot get close to it, nor can you keep it at arm's length; you cannot bestow benefit on it, nor can you do it harm; you cannot ennoble it, nor can you debase it.
Therefore it is valued by the empire.
These words, an indictment of talkers, seem frighteningly apt when applied to those who purport to tell us the meaning of life or the nature of God...things which cannot, of their nature, be expressed verbally, or at all.
Lao tzu says that the tao is like water: it sinks always to the lowest place, and nothing can make it change its essential nature. Mysterious, it runs through your fingers. Essential but elusive.
Those who know do not speak; talkers do not know.
Translation from the Chinese by D.C. Lau.