Worldly foolishness means irrationality, acting out the various idiocies of the evil inclination deluding man and deflecting him from the path of truth.
There is a defense that is used occasionally in courts of, temporary insanity. The truth of the matter is that every time a person does anything that’s wrong and unhelpful to themselves and the world around them according to the bible, it’s because at that moment they are not using their mind. You could say they where insane for doing what they did. The decision that brings about the bad choice is not the result of a clear thinking logical person, rather, it is the result of the emotions overpowering sane thinking, and it’s the immediate gratification, that takes over the long term logical consequence, or benefits that would otherwise have guided the decision process.
This is the folly of evil that is inferior to reason. In opposition to this is the "Folly of Holiness", superior to reason. That is also behavior along lines other than the rational, but it transcends reason.
When the evil inclination encompasses a person, deflecting him from the path of truth on a regular basis, he may not feel it in his power to overcome this incredible test and challenge. The more he tries to fight it rationally, the more it seems he is drawn into the mud and quagmire of the irrationality of his challenge, “What’s the solution?”
He must simply overcome this folly by its opposite force in the realm of good, by conducting himself according to the "Folly of Holiness." He must arouse his latent strength, to oppose the challenge with argumentation or explanations, but with an unswerving determination and commitment. Whatever his weakness, he shall do the opposite in the realm of good, without consideration of consequences. Here is a time, when thinking rational will keep him enmeshed in the trouble, he is trying to free himself from.
He must not immerse himself in the detailed elaboration of the human quality, but he must resist temptation, challenges, and the obstacles that are thrown in his path with 'stubborn firmness. Based on the second aspect of the soul, the essence of soul, transcending reason and intellect.
Intellect and emotion are powers of the soul, but not essence of the soul, the soul proper. The essence of soul is far higher than its powers and faculties. "For they are a stiff-necked people, so forgive" (Ex. 34:9). Their stiff-neckedness is their quality, a virtue, a reason for being forgiven. It is the granite determination of the soul to "turn from evil and do good" without rationalizing, without apologetics. The obstinate is unreasonable, much more willful, than the one who conducts himself with reason. The desires of the one who lives by reason are
controlled by reason. Intellect weakens desire, imposes limitations on it. Will and desire, not directed by intellect, is boundless. The obstinate person's will is firm and strong. That is why it is written: “nothing stands in the way of a will.”
When you truly want something – but you must truly want it – nothing will stand in your way’and “In the direction that a person will to go – he will be brought there.” The guaranteed way comes by putting the mind aside and committing ones determination in that direction.