11 A fool uttereth all his mind: but a wise man keepeth it in till afterwards.
1. It is a piece of weakness to be very open: He is a fool who utters all his mind,–who tells every thing he knows, and has in his mouth instantly whatever he has in his thoughts, and can keep no counsel,–who, whatever is started in discourse, quickly shoots his bolt,–who, when he is provoked, will say any thing that comes uppermost, whoever is reflected upon by it,–who, when he is to speak of any business, will say all he thinks, and yet never thinks he says enough, whether choice or refuse, corn or chaff, pertinent or impertinent, you shall have it all.
2. It is a piece of wisdom to be upon the reserve: A wise man will not utter all his mind at once, but will take time for a second thought, or reserve the present thought for a fitter time, when it will be more pertinent and likely to answer his intention; he will not deliver himself in a continued speech, or starched discourse, but with pauses, that he may hear what is to be objected and answer it.
Non minus interdum oratorium est tacere quam dicere–True oratory requires an occasional pause. Plin. Ep. 7.6.
– Matthew Henry Commentary