22 ¶ Though thou shouldest bray a fool in a mortar among wheat with a pestle, yet will not his foolishness depart from him.
In Proverbs we have been taught that foolishness is the opposite of knowledge.
Proverbs 12:23 A prudent man concealeth knowledge: but the heart of fools proclaimeth foolishness.
Proverbs 15:2 The tongue of the wise useth knowledge aright: but the mouth of fools poureth out foolishness.
Proverbs 15:14 The heart of him that hath understanding seeketh knowledge: but the mouth of fools feedeth on foolishness.
And that it is sin, not just silliness as some would use the word today.
Proverbs 24:9 The thought of foolishness is sin: and the scorner is an abomination to men.
Solomon, in Ecclesiastes, links it to madness and wickedness;
Eclesiastes 7:25 I applied mine heart to know, and to search, and to seek out wisdom, and the reason of things, and to know the wickedness of folly, even of foolishness and madness:
Eclesiastes 10:13 The beginning of the words of his mouth is foolishness: and the end of his talk is mischievous madness.
Look at the company it keeps, according to the Lord Jesus Christ;
Mark 7:20 And he said, That which cometh out of the man, that defileth the man. 21 For from within, out of the heart of men, proceed evil thoughts, adulteries, fornications, murders, 22 Thefts, covetousness, wickedness, deceit, lasciviousness, an evil eye, blasphemy, pride, foolishness: 23 All these evil things come from within, and defile the man.
Here, in this Proverb, a fool’s foolishness, which is clearly more than just some kind of silliness or childishness, can’t be separated from him. Remember, in context, this verse is right after a verse about seeing what a man’s true character is by how he handles praise.
John Gill points out several verses in relation to this verse, like Isaiah 1:5 and Jeremiah 5:3 concerning Judah.
Isaiah 1:5 Why should ye be stricken any more? ye will revolt more and more: the whole head is sick, and the whole heart faint.
Jeremiah 5:3 O LORD, are not thine eyes upon the truth? thou hast stricken them, but they have not grieved; thou hast consumed them, but they have refused to receive correction: they have made their faces harder than a rock; they have refused to return.
A fool will continue to do evil no matter how hard he is pressed or punished. He simply will not change because it is part of his nature to do what he does. A fool will not even so much as believe in God.
Psalm 14:1 «To the chief Musician, A Psalm of David.» The fool hath said in his heart, There is no God. They are corrupt, they have done abominable works, there is none that doeth good.
This, is in spite of the fact that all existence declares the truth of God.
Psalm 19:1 «To the chief Musician, A Psalm of David.» The heavens declare the glory of God; and the firmament sheweth his handywork.
Romans 1:19 ¶ Because that which may be known of God is manifest in them; for God hath shewed it unto them. 20 For the invisible things of him from the creation of the world are clearly seen, being understood by the things that are made, even his eternal power and Godhead; so that they are without excuse: 21 Because that, when they knew God, they glorified him not as God, neither were thankful; but became vain in their imaginations, and their foolish heart was darkened. 22 Professing themselves to be wise, they became fools,
He refuses to be corrected for his wickedness: his foolishness.
Proverbs 12:15 The way of a fool is right in his own eyes: but he that hearkeneth unto counsel is wise.
If you have had the Gospel of Jesus Christ shared with you and you insist on rejecting God’s mercy and plunging willfully headlong into Hell and a burning, Christless eternity then you are a fool. If you think you are going to have eternal life with Christ on any other terms than depending on His righteousness and not your own to get to Heaven then you are a fool. If, although saved, you will not read the words of God, hear them truthfully preached, and let them change you by degrees into the person Christ wants you to be, then you are a Christian fool but a fool nonetheless. And lest the Holy Spirit of God show you mercy and break through your foolishness you will likely remain one even though you be ground up and crushed like wheat under the efforts of a mortar and pestle.