Understanding [is] a wellspring of life unto him that hath it: but the instruction of fools [is] folly.
Ver. 22. Understanding is a well spring of life.] Vena vitae - as the heart is the principle of life, the brain of sense, so is wisdom 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 show 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 between good and evil." Heb 5:14 There are that read the text, Castigalio stultorum stultitia est. It is a folly to correct or instruct a fool, for it is to no more purpose than to wash a blackmore, &c.