In 2 Corinthians 12:7-10 Paul writes, "And lest I should be exalted above measure through the abundance of the revelations, there was given to me a thorn in the flesh, the messenger of Satan to buffet me, lest I should be exalted above measure. For this thing I besought the Lord thrice, that it might depart from me. And he said unto me, My grace is sufficient for thee: for my strength is made perfect in weakness. Most gladly therefore will I rather glory in my infirmities, that the power of Christ may rest upon me. Therefore I take pleasure in infirmities, in reproaches, in necessities, in persecutions, in distresses for Christ's sake: for when I am weak, then am I strong."

Many theories have been laid on the table and discussed. What do you think and why?

OK. I'll take a "stab" at it. Here's the text.

"7 Because of the surpassing greatness of the revelations, for this reason, to keep me from exalting myself, there was given me a thorn in the flesh, a messenger of Satan to [b]torment me—to keep me from exalting myself! 8 Concerning this I implored the Lord three times that it might leave me. 9 And He has said to me, “My grace is sufficient for you, for power is perfected in weakness.” Most gladly, therefore, I will rather boast [c]about my weaknesses, so that the power of Christ may dwell in me. 10 Therefore I am well content with weaknesses, with [d]insults, with distresses, with persecutions, with difficulties, for Christ’s sake; for when I am weak, then I am strong."

Considering verse 10, it seems to me that Paul's thorn, which he considered to be some sort of "weakness", is the persecution, frequently violent, of the Jews, a group for which he had great affection. Their rejection of the Gospel must have been both emotionally and physically very painful. Now how that equates to a personal weakness is a bit difficult. It certainly could have been some sort of physical affliction, support for which can be found in Galatians in the reference to them being willing to give him their eyes.

It should also be pointed out that this thorn was given to Paul subsequent to a powerful revelation, no doubt the one described in the previous verses.

Whatever it was, the revelation of the power of God's grace was so amazing to Paul that he completely reversed his view of whatever the thorn was.

Elsewhere he tells someone "I know you would have plucked out your own eyes for me" and hints that writing is difficult. I go with the weak-eyes view, but I won't get in someone's face for it.

It is certainly possible. Kind of strange that he does not specifically state what it is.