The tongue of the wise useth knowledge aright. This means either, brings it forth opportunely, it the right time and place, or illustrates it, makes it beautiful and pleasant, as Proverbs 15:13. The wise man not only has knowledge, but can give it appropriate expression (comp.
Proverbs 16:23). Vulgate, "The tongue of the wise adorneth wisdom." The wise man, by producing his sentiments and opinions in appropriate language and on proper occasions, commends wisdom, and renders it acceptable to his hearers.
Septuagint, "The tongue of the wise knoweth what is fair ( καλά)." But the mouth of fools poureth out foolishness (Proverbs 15:28). A fool cannot open his mouth without exposing his folly; he speaks without due consideration or discretion; as the Vulgate terms it, ebullit, "he bubbles over," like a boiling pot, which emits its contents inopportunely and uselessly.
Septuagint, "The mouth of fools proclaimeth evil."