2 Cor. 12
As to the thorn in the flesh, the Lord was dealing with Paul in grace, and had apprehended him for glory. Paul was now to walk with the Lord on this new ground; but he did not know his own weakness, nor the power of the flesh in him, that would boast itself of the revelations made in grace. The Lord therefore gives him the thorn in the flesh—an aid from Himself to keep the flesh in its right place. Paul did not at first apprehend this, and three times prayed for its removal; then the Lord tells him, "My grace is sufficient for thee: for My strength is made perfect in weakness." Then Paul says, "Most gladly therefore will I rather boast in my weaknesses" (J.N.D. Trans.). Through grace he ranges himself on the side of the Lord's grace and strength, and takes pleasure in the thorn—that which shows his infirmity—instead of struggling against it, and praying for its removal.