i. e., The empty-hearted, rejoicing in folly, goes the wrong way; the man of understanding, rejoicing in wisdom, goes the right way.

Folly is joy to him that is destitute of wisdom,.... Or "that wants a heart" (q), a wise and understanding one; by "folly" is meant sin, for all sin is folly; and that is very pleasing and joyous to a wicked he chooses it and delights in it; instead of being ashamed of it, and sorry for it, he glories in it, and makes his boast of it; and not only takes pleasure in committing it himself, but also in those that do it; see Proverbs 10:23;
but a man of understanding walketh uprightly; he who has his understanding enlightened by the Spirit of God; who has an understanding given him by the Son of God; who has a spiritual and experimental understanding of the Gospel, and the truths of it: he walks according to the rule of the divine word; he walks as he has Christ for an example, and by faith on him; and after the spirit, and not after the flesh: or "directs himself in walking" (r), his goings, as the Vulgate Latin version, according to the above rule, example, and guidance, by the assistance of the spirit and grace of God; otherwise it is not in man that walketh of himself to direct his steps, Jeremiah 10:23.
(q) "carenti corde", Montanus; "ei qui deficitur", Schultens. (r) "diriget seipsum ambulando", Montanus; "diriget ambulare, vel ad ambulandum", Vatablus; "diriget viam suam ad ambulandum", Mercerus, Gejerus.

Such as are truly wise, study that their thoughts, words, and actions should be regular, sincere, and holy.

walketh uprightly--and so finds his joy (Proverbs 3:6; Proverbs 10:23).

21 Folly is joy to him that is devoid of understanding;
But a man of understanding goeth straight forward.
Regarding חסר־לב, vid., at Proverbs 6:32 (cf. libı̂b, which in the Samaritan means "dearly beloved," in Syr. "courageous," in Arab. and Aethiop. cordatus); אישׁ תּבוּנה, Proverbs 10:23, and ישּׁר, with the accus. of the way, here of the going, Proverbs 3:6 (but not Proverbs 11:5, where the going itself is not the subject). In consequence of the contrast, the meaning of 21a is different from that of Proverbs 10:23, according to which sin is to the fool as the sport of a child. Here אוּלת is folly and buffoonery, drawing aside in every kind of way from the direct path of that which is good, and especially from the path of one's duty. This gives joy to the fool; he is thereby drawn away from the earnest and faithful performance of the duties of his calling, and thus wastes time and strength; while, on the contrary, a man of understanding, who perceives and rejects the vanity and unworthiness of such trifling and such nonsense, keeps the straight direction of his going, i.e., without being drawn aside or kept back, goes straight forward, i.e., true to duty, prosecutes the end of his calling. לכת is accus., like Proverbs 30:29, Micah 6:8.