Aquinas as Biblical Exegete

His Interpretation of Paul’s “Thorn in the Flesh”

No doubt Thomas Aquinas is most famous as a systematic theologian who made great use of philosophical sources such as Aristotle’s Metaphysics. Nevertheless, when Aquinas first taught at the University of Paris, he held the title of Magister in Sacra Pagina, and the “sacred page” referred to in that academic title was not the Metaphysics of Aristotle, but rather the Bible. Moreover, Aquinas’s theological masterpiece, the Summa Theologiae, not only begins with an acknowledgment of the importance of the Bible (Prima Pars, Question 1, first article, sed contra) but the work is replete not just with references to Aristotle, but rather with references to the Bible. As an illustration of Aquinas’s mastery of the Bible, in this essay I examine his interpretation of a passage from Saint Paul.

In his Second Letter to the Corinthians, chapter 12, verses 7–8, Paul tells us:

Therefore that I might not become too elated, a thorn in the flesh was given to me, an angel of Satan, to beat me to keep me from being too elated. Three times I begged the Lord about this, that it might leave me, but he said to me, “My grace is sufficient for you, for power is made perfect in weakness.”1

That Biblical passage has been the object of various exegetical interpretations from early Christian history to modern times. But Aquinas’s exegesis of that passage holds a special place.

The earliest Christian tradition interpreted Paul’s “thorn in the flesh” and “angel of Satan” as references to a physical malady. For example, we have the early witness of the devout North African layman and lawyer Tertullian (c. 155 – c. 240 AD). In Tertullian’s treatise on purity, De pudicitia, he refers to 2 Cor 12:7–8, saying: “This exaltation was checked in the Apostle by buffets, if you will; that is, by ear or head ache.”2 Ambrose of Milan (c. 340–97), in his Two Books Concerning Repentance, book 1, chapter 14, also identifies Paul’s “thorn in the flesh” as a physical ailment: “Scripture testifies that Satan is the author of this bodily suffering,” and then he quotes from 2 Cor 12:7.3 Ambrose’s contemporary, Basil, bishop of Caesarea (329–79), in his Asketikon, his “longer response” to questions regarding the ascetic or monastic life, question 55, says of 2 Cor 12:7–8: “We find yet another cause of illnesses happening to the saints, as in the case of the Apostle. In order that he might not seem to exceed the bounds of human nature and that no one should think that he was possessed of something exceptional in his human nature — which the Lycanonians thought, when they brought him garlands and oxen (cf. Acts 14:12) — illness was his lot continually, in order to make plain his own human nature (cf. 2 Cor 12:7).”4

Consider also the opinion of Saint Jerome (347–420), the great biblical scholar. While Jerome was working in Rome as secretary to Pope Damasus I, during the years 382–85, he made the acquaintance of a wealthy pious Roman widow, Paula, whose spiritual director he soon became. Jerome wrote a letter to Paula to console her upon the death of her daughter Blaesilla, who had died from some serious illness. Therein Jerome quotes from Paul’s Second Letter to the Corinthians 12:8–10 to show to Paula how even those most blessed by God are sometimes made to suffer illness: “Am I in health? I thank my Creator. Am I sick? In this case, too, I praise God’s will. For ‘when I am weak, then am I strong;’ and the strength of the spirit is made perfect in the weakness of the flesh. Even an apostle must bear what he dislikes, that ailment for the removal of which he besought the Lord thrice.”5

However, not all writers in the Patristic era made that same interpretation. John Chrysostom (c. 349–407) is the great exception. More than once in his writings Chrysostom makes clear that he rejects the idea that Paul suffered from physical ailments. Instead, Chrysostom insists “the thorn in the flesh” and “angel of Satan” which Paul refers to in Second Corinthians 12 is a reference to human opponents; human opponents such as Alexander the Coppersmith (in 2 Tim 4:14) or Hymenaeus and Philetus (in 2 Tim 2:17). For example, in the spring of 387, the emperor Theodosius I levied a new and severe tax on his people. At Antioch in Syria, where Chrysostom was serving as priest at the cathedral, there were riotous protests against the new tax, protests which included the casting down of the emperor’s statue. To quell such rioting, Chrysostom delivered a series of homilies. In the first of his “Homilies Concerning the Statues,” Chrysostom reminds his congregation how Saint Paul too had to face powerful opposition, recalling Paul’s words in Second Corinthians 12 but explaining: “by messenger of Satan, indeed, he means not particular demons, but men ministering for the devil, the unbelievers, the tyrants, the heathens, who perseveringly molested, and unceasingly worried him.”6 Later when Chrysostom served as bishop in Constantinople, he had as one of his principal assistants the Deaconess Olympia. We have a letter which he wrote to her, a letter in which Chrysostom once again refers to Paul’s words in Second Corinthians 12, this time saying: “For although he was not subjected to bodily infirmity, yet he was buffeted by trials not less severe, which inflicted much physical pain.” And thus Chrysostom insists Paul’s words about “a thorn in the flesh” and “an angel of Satan” refer to “the blows, the bonds, the chains, the imprisonments, the being dragged about, and maltreated.”7

In the Middle Ages, however, there arose a third interpretation. Peter Damian (1007–72), in his letter 160, section 18, suggests it was not a physical ailment nor enemy’s wrath from which Paul suffered, but instead it was a temptation: “Even though the soul of every just man is now making progress toward higher goals, it is still brought down to baser things by temptation, so that surging pride does not cause him to boast of his virtues. Indeed, temptation is the goad that is useful in guarding humility. Hence, the apostle says: ‘And so, to keep me from being unduly elated by the magnificence of such revelations, I was given a thorn for my flesh which came as Satan’s messenger to bruise me.’”8

Thomas Aquinas (1225–74), however, is even more precise as to the nature of this temptation which Paul suffered, for he interprets “thorn in the flesh” as a reference to sexual temptations. When he was teaching at the University of Paris, 1252–56, Aquinas not only wrote a commentary on Paul’s letters to the Corinthians, but he also addressed 2 Cor 12:7–8 in a sermon. In his Commentary on II Corinthians, lecture 3, he identifies Paul’s “a sting of my flesh” as a reference to “concupiscence arising from my flesh.”9 Once again, a few paragraphs later, Aquinas identifies Paul’s weakness as “this weakness of concupiscence.”10 Aquinas makes yet another reference to Paul’s “thorn in the flesh” in a sermon which he gave on the “the last-but-one Sunday before Lent, ‘Sexagesima.’” There he says: “Passions of the soul are called thorns (cf. 2 Cor 12:7) because, as thorns mutilate the body, so the passions of cupidity mutilate the soul.”11

Though we cannot survey all the later interpretations of Second Corinthians 12:7–8 — that is, interpretations after Aquinas — it is interesting to note those of such prominent Christian figures as Luther, Calvin, and Newman.

The young reformer Martin Luther (1483–1546) wrote in 1519 (two years after having posted his 95 Theses at Wittenburg) an essay entitled “Discussion on How Confession Should Be Made.” There, Luther cites Second Corinthians 12:7 in his treatment of sexual temptations:

I am content with the fact that not all sins of the heart have to be confessed. But if some are to be confessed, I assert that it should be only those which a man himself clearly knows to have established themselves in his heart against the divine commandments; that is, not simple thoughts about a virgin or a woman, nor, on the other hand, a woman’s thoughts about a young man; nor affections themselves or the ardor of mutual lust, or the inclinations toward the opposite sex, however filthy; nor, I would add, any passions of this sort. For such thoughts are frequently passions — aroused by the flesh, by the world, or by the devil — which the soul is forced to bear against its will, sometimes for a long time, occasionally indeed for a whole day or a week, just as the apostle Paul confesses about his ‘thorn in the flesh’ [II Cor. 12:7].12

However, John Calvin (1509–64), the other great Protestant Reformer, takes a radical stance in denying that Paul’s words are an indirect reference to concupiscence. Indeed, Calvin’s interpretation of Paul’s “thorn in the flesh” seems almost a direct and scornful denial of Aquinas’s interpretation. Calvin says in his Commentary on the Epistles of Paul the Apostle to the Corinthians:

Those act a ridiculous part, who think that Paul was tempted by lust. We must therefore repudiate that fancy. Some have supposed, that he was harassed with frequent pains in the head. Chrysostom is rather inclined to think, that the reference is to Hymeneus and Alexander, and the like, because, instigated by the devil, they occasioned Paul very much annoyance. My opinion is, that under this term is comprehended every kind of temptation, with which Paul was exercised. For flesh here, in my opinion, denotes — not the body, but that part of the soul which has not yet been regenerated.13

It is also interesting to note the opinion of John Henry Newman. Newman’s work called Parochial and Plain Sermons is a collection of the sermons which he preached on Sundays and feast days from the pulpit of his Anglican parish at Oxford, the Church of Saint Mary the Virgin, sermons preached between the years 1825 and 1845. Among those sermons is one entitled “Temporal Advantages.” There Newman quotes Paul’s reference to a “thorn in the flesh,” but insists it is an intentionally ambiguous and vague reference. In that sermon, Newman was treating of ambition and covetousness as “sins common to men at all times.” But, as a contrast, Newman offers the example of Saint Paul, who instead suffered another form of temptation:

Even the best men require some pain or grief to sober them and keep their hearts right. Thus, to take the example of St. Paul himself, even his labours, sufferings, and anxieties, he tells us, would not have been sufficient to keep him from being exalted above measure, through the abundance of the revelations, unless there had been added some further cross, some “thorn in the flesh,” as he terms it, some secret affliction, of which we are not particularly informed, to humble him, and to keep him in a sense of his weak and dependent condition.14

But we should also look at the opinions of some notable Catholic writers: the great mystic John of the Cross and the great exegete Cornelius a Lapide.

Spanish mystic and Carmelite friar John of the Cross lived from 1542 to 1591. In the years 1582–85 he wrote a treatise on the spiritual life which he entitled The Dark Night. There in book 2, chapter 14, without any reference to Aquinas, John says: “An angel of Satan [2 Cor. 12:7], which is the spirit of fornication, is given to some to buffet their senses with strong and abominable temptations, and afflict their spirit with foul thoughts and very vivid images, which sometimes is a pain worse than death for them.”15

Yet one more opinion worthy of our consideration is that of the Belgian Jesuit and biblical exegete Cornelius a Lapide (1567–1637). After his ordination in 1592, Lapide taught Scripture for the next forty years, first at the University of Louvain (1596–1616) and then at the Jesuit College at Rome (1616–36). During those forty years of teaching, Lapide also did intensive research and extensive writing, composing enormous commentaries on all the books of the Bible with the exception of Job and Psalms. Moreover, Lapide’s writings exhibit not only a knowledge of Hebrew, Greek, and Latin, but also of theology, Patristic literature, and Church history. He soon came to be regarded with esteem even by Protestant scholars, who regarded him as the foremost Catholic authority on Scripture. Indeed, in 1876, Anglican clergyman Thomas Mossman published his translation of Lapide’s writings under the title of The Great Commentary of Cornelius a Lapide. Among all Lapide’s published works, however, the most esteemed was his commentary on the letters of Paul, Commentaira in omnes Divi Pauli Epistolas (Antwerp 1614). And it is there, in his commentary on Second Corinthians chapter 12, that Lapide takes his position with those who see Paul’s “thorn in the flesh” as a reference to sexual temptations:

It may be asked: “Why, then, does he call this thorn ‘the messenger of Satan,’ or the minister of Lucifer?” I reply that he means by the messenger of Satan, Satan himself, as the exciting cause of this thorn of concupiscence; or even he calls the thorn sent by Satan, the adversary of his chastity, by the name of Satan. This would be a metonymy, where the cause is put for the effect, the agent for his work. For the devil, by stirring up the humours, by kindling the blood, by inflaming the feelings that subserve generation, by putting foul images before S. Paul’s mind, gave life to that concupiscence which had been as it were put to sleep, and mortified by his numerous labours, fastings, and troubles. Thus he stirred up S. Paul to obey the foul motions of lust.16

It is also interesting to note that Lapide at this point, in his very next sentence, adds as evidence to support his identification of Paul’s “thorn in the flesh” as concupiscence: “it is proved, from Rom. vii, that this concupiscence was in S. Paul, for there he bewails it more than he does here” (ibid.).

However, of all these opinions regarding the proper interpretation of Paul’s “thorn in the flesh” and “angel of Satan,” it is Calvin’s position that seems to have triumphed among modern exegetes. Calvin’s rejection of the identification of Paul’s “thorn in the flesh” and “angel of Satan” as indirect references to sexual temptations is an opinion shared by many modern biblical critics. For example, note the judgment of Scotsman William Barclay (1907–78), longtime Professor of Biblical Criticism at the University of Glasgow. Barclay, in his commentary The Letters to the Corinthians, says: “It has been taken to mean carnal temptations. When the monks and the hermits shut themselves up in their monasteries and their cells they found that the last instinct that could be tamed was that of sex. They wished to eliminate it but it haunted them. They held that Paul was like that; and this is the common Roman Catholic view to this day.”17 1978), 257.]

If that was once “the common Roman Catholic view,” things changed in the late twentieth century. Take for example the footnote to that passage in the New American Bible translation, revised 1986, which tells us:

A thorn in the flesh: variously interpreted as a sickness or physical disability, a temptation, or a handicap connected with his apostolic activity. But since Hebrew “thorn in the flesh,” like English “thorn in my side,” refers to persons (cf. Numbers 33:55, “those whom you allow to remain will become as barbs in your eyes and thorns in your side, and they will harass you”; Ezekiel 28:24, “Sidon shall no longer be a tearing thorn for the house of Israel, a brier that scratches them more than all the others”), Paul may be referring to some especially persistent and obnoxious opponent.

Consider also the opinion of Irish Dominican priest, and professor of the New Testament at the Ēcole Biblique in Jerusalem, Jerome Murphy O’Connor (died 2013). O’Connor, in his comprehensive biography of Paul’s life, says:

The vast majority of scholars consider that Paul had a physical ailment or a psychic problem. The suggestions — and they cannot be considered anything more — regarding the latter betray a very refined imagination: a real demon, who accompanied Paul on his heavenly journey, agony at the refusal of the Jews to respond to the gospel, sexual temptations, hysteria, depression. Somatic illnesses appear to have a better foundation: epilepsy (Paul fell to the ground during his conversion, Acts 9:4), poor eyesight (he desired the eyes of the Galatians, Gal. 4:15), a speech defect (he made a bad first impression, Gal. 4:13 ff., and spoke badly, 2 Cor 10:10; 11:6), recurring malarial fever, headache or earache.18

But in his conclusion O’Connor sides with John Chrysostom: “The only hypothesis for which a serious case can be made is that by the thorn in his flesh Paul meant opposition to his ministry.”19

In response to this modern majority, I suggest that we should not be so quick to dismiss Aquinas’s identification of Paul’s “thorn in the flesh” and “angel of Satan” as references to sexual temptations. Consider how concupiscence is a major theme in Paul’s writings. Moreover, Paul makes a point of how he has personally handled the challenge of concupiscence. I am referring to Paul’s words in First Corinthians 7:1–8, wherein Paul gives advice to the married but concludes with reference to his own option for celibacy:

Now in regard to the matters about which you wrote: “It is a good thing for a man not to touch a woman,” but because of cases of immorality every man should have his own wife, and every woman her own husband. The husband should fulfill his duty toward his wife, and likewise the wife toward her husband. A wife does not have authority over her own body, but rather her husband, and similarly a husband does not have authority over his own body, but rather his wife. Do not deprive each other, except perhaps by mutual consent for a time, to be free for prayer, but then return to one another, so that Satan may not tempt you through your lack of self-control. This I say by way of concession, however, not as a command. Indeed, I wish everyone to be, as I am, but each has a particular gift from God, one of one kind and one another.

Now to the unmarried and to widows I say: it is a good thing for them to remain as they are, as I do . . . .

Indeed, it can be argued that Paul’s First Letter to Timothy 5:9–11 witnesses to Paul’s creation of an order of widows, devout Christian women with a “pledge” not to marry. But Paul appears quite aware of the temptations to break one’s “pledge”:

Let a widow be enrolled if she is not less than sixty years old, married only once, with a reputation for good works, namely, that she has raised children, practiced hospitality, washed the feet of the holy ones, helped those in distress, involved herself in every good work. But exclude younger widows, for when their sensuality estranges them from Christ, they want to marry and will incur condemnation for breaking their first pledge.

And thus one can conclude: Aquinas’s conjecture that Paul’s “thorn in the flesh” and “angel of Satan” are references to sexual temptations is hardly gratuitous, but instead is based upon a real psychological as well as moral link between the celibacy of Saint Paul and that of medieval monks and hermits.

  1. New American Bible, revised edition of 1986.
  2. Tertullian: Treatises on Penance, trans. W.P. Le Saint, Ancient Christian Writers, vol. 28 (Ramsey, NJ: Newman Press, 1959), 88.
  3.  St. Ambrose: Select Works and Letters, Nicene and Post-Nicene Fathers, Second Series, vol. 10 (Grand Rapids: Eerdmans, 1976), 342.
  4. This is a quotation from The Asketikon of St. Basil the Great, trans. Anna M. Silvas (Oxford University Press, 2005), 268–69.
  5. Letter 39, St. Jerome: Letters and Select Works, The Nicene and Post Nicene Fathers, Second Series, vol. 6; 50.
  6. Saint Chrysostom, Nicene and Post-Nicene Fathers, First Series, vol. 9; 337.
  7. Saint Chrysostom, 295.
  8. Peter Damian: Letters 151–180, trans. O.J. Blum and I.M. Resnick, Fathers of the Church: Medieval Continuation, vol. 7 (Wash., D.C.: CUA Press, 2005), 119–20.
  9. Thomas Aquinas, Commentary on the Letters of Saint Paul to the Corinthians, trans. F.R. Larcher, B. Mortensen, and D. Keating (Lander, Wyoming: Aquinas Institute for the Study of Sacred Doctrine, 2012), 601.
  10. Aquinas, Commentary on Corinthians, 602.
  11. Thomas Aquinas: The Academic Sermons, trans. M.R. Hoogland (Wash., D.C.: CUA Press, 2010), 125.
  12. Luther’s Works: Church and Ministry I, ed. E.W. Gritech, vol. 39 (Philadelphia: Fortress Press, 1970), 33–34.
  13. Calvin, Commentary on the Epistles of Paul the Apostle to the Corinthians, trans. J. Pingle (Grand Rapids: Eerdmans, 1959), 373–74.
  14. John Henry Newman, Parochial and Plain Sermons, vol. 7 (London: Longman, Green, and Co., 1891), 68.
  15. The Collected Works of S. John of the Cross, trans. K. Kavanaugh and O. Rodriguez (Wash., D.C.: Institute of Carmelite Studies, 1979), 328.
  16. The Great Commentary of Carnelius a Lapide: II Corinthians and Galatians, trans. W.F. Cobb, vol. 8 (Edinburgh: John Grant, 1908), 187.
  17. William Barclay, The Letters to the Corinthians (Philadelphia: Westminster Press, [1957
  18. Jerome Murphy-O’Connor, Paul: A Critical Life (Oxford: Clarendon Press, 1996), 321.
  19. Murphy-O’Connor, Paul, 321.
Lawrence B. Porter, STL, PhD About Lawrence B. Porter, STL, PhD

Lawrence B. Porter, STB, STL, STLr, PhD, is a priest of the Archdiocese of Newark, NJ, and a professor of systematic theology in the Seminary/School of Theology at Seton Hall University in South Orange, NJ. In his thirty years of teaching, Porter has published two books, A Guide to the Church (2008) and The Assault on Priesthood (2012), and more than thirty articles in various pastoral and theological journals. Porter regularly presides and preaches at the noon time Sunday Mass at St. Catherine of Siena Church in Hillside, NJ.


  1. Avatar Bernadette. Fakoory says:

    Is it possible that all these opinions of the wise and learned in regard to what St.Paul meant by a thorn in his flesh is a transference of their interior struggle with their flesh or exterior enemy on the outside that obstructs the freedom of their spirit.

    Undoubtedly, we all have to deal with the seven deadly sins. But, the vice of lust of the eyes or the flesh is deadliest. I believe it is what God refers to as the lion that roars waiting to devour us. Lust of the eyes and the flesh is interconnected and the reason it is most deadly is that it is close to our sense of taste and touch which speaks to the core of our being. It hinges on the uncontrollable irascible and concupisible desires. These desires in its raw stages is what keeps us confuse and blurs our vision of the good and virtuous desire.

    Getting ahead the irrasible and concupiscible desires is actually getting beyond the veil of the flash to the spirit level where there is real victory. Perhaps when St.Paul thought he was making headway in his spiritual life lived in God to that advantageous point in his journey of faith he is suddenly thrown for a loop by a snag on the way that makes him aware that he is still vulnerable in the flesh which is still apart of his being in this world.

    Thank you

  2. Avatar Donald Paul says:

    I have had St. Paul as my patron saint all my life. From my baptism at 11 months, where the ministering priest upon discovering both of my parents were Protestant said: “He’s an ‘apostle to the Gentiles’! Then he needs the “Apostle of the Gentles” for his patron saint.”, until now because I kept him as my patron for Confirmation. After a very powerful mystical revelatory experience, God went out to give me the spiritual gift that Paul was talking about here, but I was 16 or 17 and too shaken and immature to handle it. I distinctly remember hearing God say: “OK, then give it to him gradually.” Later, when I returned to the practice of the Faith after a lapse by going to daily Mass, I experienced the spiritual gift gradually growing in strength and intensity within me and it remains to this day. The “thorn in the flesh” is an involuntary frown and the “angel of Satan” is an involuntary smile. Both happen or not at will of the Spirit in reaction to the thoughts of others whether I know them or not. I am not reading their thoughts, mind you, only reacting to them. After which I stop and try to figure out on my own what it could be about. Sometimes it’s clear and many times it remains a puzzle. You just learn to deal with it and trust the Holy Spirit. You remain free to look away or bite or purse your lips (with the smile) if you don’t agree with or like what either response can signify or be misconstrued to signify at times. I am amazed that it’s only Catholic English translations that consistently and persistently keep the word angel and don’t change it to minister. It’s like the Holy Spirit is holding the Catholic bible scholars back from messing with the original Greek word that He inspired and because of it I could figure out how my spiritual gift was corresponding to this verse.