Bede, on Prov 12:23

“A cautious man concealeth knowledge: and the heart of fools publisheth folly.”

“And the heart of fools proclaims foolishness. When they either desire to know more than they should, and leap to thinking that foolishness is wisdom; or certainly when trying to teach others who cannot yet understand, they provoke them to greater foolishness, and like forcing the sun's light on small eyes, they take away the little light they seemed to see.”

Imported from an open dataset — not yet checked against the printed edition.