Contemporary Bible teacher Les Feldick has put forth one of the best guesses I've seen concerning Paul's 'thorn in the flesh':

 

II Corinthians 12:7

"And lest I should be exalted above measure through the abundance of the revelations,..."

See how plain that is when you know now what he is talking about? What was the abundance of the revelations? Well, first the revelations of these doctrines of Grace, the Gospel, and the Church Age teachings that he got to share, but on top of that he got a glimpse of glory, a revelation, and the man is bursting to tell about that experience. And yet God says in so many words, that, "I don't want you to get the big head, I don't want you to get proud, and so I'm going to give you a thorn in the flesh to keep you humble."

II Corinthians 12:7b

"...there was given to me a thorn in the flesh, the messenger of Satan to buffet me, lest I should be exalted above measure."

Now the Greek makes it so much stronger. I'm not a Greek scholar, but a few of these verses I go back and do a little study on. Do you know what Paul is actually calling here this thorn in the flesh? It was like being crucified. It was that kind of a constant pain. It was as if he was constantly suffering crucifixion. Now that is what the Greek actually implies. In order to keep Paul humble, the Lord had given him a thorn in the flesh that was like an impalement that he had to live with: and he's already had it over fourteen years. And we have to assume that he carried it to his death. Now there's a lot of controversy from various points of view as to what his thorn in the flesh was. Some of them are absurd, and some make some sense, but the one that I still stand on is this: I think he had a vicious case of pink eye. It was very common in the ancient world and they didn't have the antibiotics and so forth, and it would lead to his repulsive appearance. Those matterly eyes effected his eye sight as we see in the Book of Galatians.

Galatians 4:15

"Where is then the blessedness ye spake of? for I bear you record, that, if it had been possible, ye would have plucked out your own eyes, and have given them to me."

Why would they want to give him their eyes if he didn't have a need for them? Then the next one is in Chapter 6.

Galatians 6:11

"Ye see how large a letter (large print) I have written unto you with mine own hand."

Who uses large print? Blind people.

 

Phil 2