Hastings' Dictionary of the Bible (1898)
THORN IN THE FLESH, PAUL'S. In two passages, 2 Cor 12:7-10 and Gal 4:14-15, Paul alludes to some circumstance or infliction which hindered his ministry; but, as he does not say what it was, but calls it merely a "stake in the flesh," there have been numerous conjectures. " The explanations which have at various times been advanced may be divided into three classes: Spiritual trials. - Either sensual temptations, as is the favorite view of Roman Catholic writers, or temptations to unbelief, doubts arising from the memory of his sinful past; so Luther and Calvin and other of the Reformers.
External calamities. - Either his persecutions and sufferings or else his Judaizing opponents, as Chrysostom and the Greek Fathers thought. But some of the ancient and mediaeval as well as the modern commentators have been dissatisfied with these explanations because they do not meet the difficulty, and accordingly have favored - Some bodily ailment. - Almost every disorder - pleurisy, the stone, defect of utterance, hypochrondria, headache, earache, epilepsy, acute ophthalmia - has been suggested and advocated by the fathers and schoolmen.
Tradition supports the notion that the "thorn" was some sort of pain in the head. According to modern opinion, the choice lies between epilepsy and acute ophthalmia. In favor of the former is the life Paul led, his trances, his enthusiasm followed by depression, his enormous nervous strain; this would be enough to shatter his system. But against any such notion is Paul's physical activity, his balanced mind, his self-control, and his confidence. No such objection seems to lie against acute ophthalmia - a disease which is quite common in the East.
It may well have been caused in his case by the bright light which fell upon his eyes at his conversion, and increased, or at least not lessened, by his wandering, laborious life. There are many indications that this interpretation of the "thorn" is correct. " The disfigurement it causes would have made him the object of contempt and loathing he represents himself to have been. Gal 4:14; 2 Cor 10:10. Paul's failure to recognize the high priest.
Acts 23:5; his dread of being left alone, shown by his allusions to it as a trial, 1 Thess 3:1; 2 Tim 4:16; his expression, "Ye see with what large letters I write unto you with my own hand," Gal 6:11; his employment of an amanuensis for at least the major part of his Epistles, cf. Rom 16:22, - these are facts looking in the same direction. Accepting this interpretation, what light it throws upon the life of Paul! How it elevates our conception of his heroism! how it in creases our respect for his work!
We see that he was not able to move about or write as he would, but was dependent upon others; and yet, notwithstanding his suffering and his persecutions, his dimmed vision and his interrupted toil, he struggled and labored for his Master unto death.