John Trapp on Proverbs 16:22

Verſ. 22. Underſtanding is a well-ſpring of life] Vena vitae: as the heart is the principle of life, the brain of ſenſe; ſo is wiſdome in the heart, of all good carriage in the life, and of a timely laying hold upon eternal life: beſides the benefit that other men make of it, by fetching water thence as from a common Well.

But the inſtruction of fools is folly] When they would ſhew moſt gravity, they betray their folly; they act not from an inward principle, therefore they cannot quit themſelves ſo, but that their folly at length will appear to all men that have their ſenſes exerciſed to diſcern betwixt good and evil. There are that read the Text, Caſtigatio ſtultorum ſtuititia eſt, It is a folly to correct or inſtruct a fool; for it is to no more purpoſe than to waſh a Blackmore, &c.