A fool uttereth all his mind - A man should be careful to keep his own secret, and never tell his whole mind upon any subject, while there are other opinions yet to be delivered; else, if he speak again, he must go over his old ground; and as he brings out nothing new, he injures his former argument.
Mind - The Hebrew word is used sometimes for “mind” or “reason,” sometimes for “passion,” or “wrath.” The reticence commended would include both; but the verb “keepeth it in” (rendered “stilleth,” in Psalm 65:7) is slightly in favor of the second of the two senses.