John Trapp on Proverbs 12:23

Verſ. 23. A prudent man concealeth knowledge] ſcil. Till hee findes a fit time to vent it; for then, the lips of the wiſe do ſpread abroad knowledge, Chap. 15.7. hee is no niggard where there is need, but loves not to outlaſh. Taciturnity is a virtue with him, Tacitus a good hiſtorian.Curtlus. lib. 4 Perſae magnam rem ſuſtineri poſſe non credunt ab eo cui tacere grave ſit. The Perſians hold not him fit for great imployments, that cannot keep counſel, ſaith Curtius.

But the heart of fools proclaimeth fooliſhneſs] In it is, and out it muſt: Pleni rimarum ſunt, they can keep no counſel, hold no ſecrets, muſt needs tell all, whatever come of it: ut qui nec tacere nec prudenter loqui noriut, they can neither hold their tongue, nor uſe it to purpoſe. The Moraliſt adviſeth [non-Latin text not transcribed] either to ſay nothing, or that which is better than nothing. And Socrates being asked by one how hee might have the reputation of a wiſe man? Friſt, ſaid hee, thou muſt hold thy tongue oftner than ſpeak: Secondly, thou muſt learn how to frame thy ſpeeches.