Note, 1. He that is wise does not affect to proclaim his wisdom, and it is his honour that he does not. He communicates his knowledge when it may turn to the edification of others, but he conceals it when the showing of it would only tend to his own commendation. Knowing men, if they be prudent men, will carefully avoid every thing that savours of ostentation, and not take all occasions to show their learning and reading, but only to use it for good purposes, and then let their own works praise them. Ars est celare artem - The perfection of art is to conceal it. 2. He that is foolish cannot avoid proclaiming his folly, and it is his shame that he cannot: The heart of fools, by their foolish words and actions, proclaims foolishness; either they do not desire to hide it, so little sense have they of good and evil, honour and dishonour, or they know not how to hide it, so little discretion have they in the management of themselves, Ecc 10:3.

A prudent man concealeth knowledge,.... Of things natural or divine, which he is furnished with; not but that he is willing to communicate it, as he should, at proper times, in proper places, and to proper persons; but he does not needlessly and unseasonably speak of it; he does not make a show of it, or boast and brag of it: he modestly forbears to speak of what he knows, but when there is a necessity for it, even of that which may be lawfully divulged; which is a point of prudence and modesty; otherwise it is criminal to reveal secrets, or publish what should be kept private or should not be known. Aben Ezra interprets it of a wise man's hiding his knowledge in his heart, that he may not forget it;

but the heart of fools proclaimeth foolishness; that which they have in their hearts and minds, and which they take for deep knowledge, profound and recondite learning, they proclaim with their mouths in a noisy and clamorous way; and while they declare their ill shaped notions, their incoherent and unconnected ideas of things, they betray their ignorance and folly, as ostentatious men do.

concealeth--by his modesty (Pro 10:14; Pro 11:13).

heart . . . proclaimeth--as his lips speak his thoughts (compare Ecc 10:3).