Thomas Aquinas Commentary John 21:18-19

"Verily, verily, I say unto thee, When thou wast young, thou girdedst thyself, and walkedst whither thou wouldest: but when thou shalt be old, thou shalt stretch forth thy hands, and another shall gird thee, and carry thee whither thou wouldest not. Now this he spake, signifying by what manner of death he should glorify God. And when he had spoken this, he saith unto him, Follow me." — John 21:18-19 (ASV)

1. Above, our Lord entrusted the office of shepherd to Peter. Now He foretells his martyrdom. This was fitting because a good shepherd should lay down his life for his sheep (John 10:11).

   It was not granted to the young Peter to lay down his life for Christ; rather, it was for the old Peter to lay down his life for his sheep. This is what Christ foretold to him.

   Christ first tells of Peter’s past life, then He predicts the end of his future life: when you are old, you will stretch forth your hands.

   Third, the Evangelist explains our Lord’s words: and he said this to signify by what death he should glorify God.

2. Peter’s past life showed certain shortcomings, for as a young man he was too presumptuous and self-willed. But this is characteristic of the young, as the Philosopher says in his Rhetoric. Thus we read in Ecclesiastes a kind of reproach: rejoice, O young man, in your youth, and let your heart cheer you in the days of your youth; walk in the ways of your heart and the sight of your eyes (Ecclesiastes 11:9).

   Our Lord refers to this trait of Peter and says, when you were younger, you girded yourself and walked where you wanted. He says, you girded yourself, meaning you restrained yourself from certain unlawful and superfluous things, and walked where you wanted, not allowing yourself to be kept in check by anyone. This is why you always wanted to be in danger for My sake.

   But it was not granted that you should suffer for Me when young. Instead, when you are old I will fulfill your desire, because you will stretch forth your hands, and another will gird you. What a remarkable prediction! It gives both the time and the nature of the suffering. From the time these words were spoken until Peter’s death, about thirty-seven years went by. We can see from this that Peter was quite old.

3. According to Chrysostom, He says, when you are old, because human affairs are different from divine affairs. In human affairs, the young are useful, and the old are not of much use; but in divine matters, virtue is not taken away by old age but sometimes becomes even stronger: my old age is exalted in abundant mercy (Psalms 92:10); as the days of your youth, so will your old age be (Deuteronomy 33:25). But as Cicero says, this is to be understood only of those who have practiced virtue in their youth. For those who have passed their youth in idleness will become of little or no value when old.

   This also teaches us that we rarely find rulers and teachers who are useful to the Church dying young, as Origen remarks in his explanation of Matthew: now after a long time the master of those servants came (Matthew 25:19). He gives Paul as an example. In Acts, Paul is seen as a young man (Acts 7:58), but in Philemon, he is an old man (Philemon 1:9). The reason for this is that people of this caliber are so rare that when they are found, the Lord preserves them to a ripe old age.

4. He mentions the way Peter will suffer when He says, you will stretch forth your hands, for Peter was crucified. Yet he was crucified using ropes, not nails, so that he would not die so quickly. This is the “girding” spoken of by Christ.

   Three things can be considered in the sufferings of the saints. First is the impulse of natural affection: there is such a natural love between the soul and the body that the soul never desires to be separated from the body, nor the body from the soul: not that we would be unclothed, but that we would be further clothed (2 Corinthians 5:4); my soul is very sorrowful, even to death (Matthew 26:38). This is why Christ says, where you do not want, that is, according to the impulse of nature, which is so rooted in us that even old age could not destroy it in Peter. However, the desire that comes from grace weakens this natural impulse: my desire is to depart and be with Christ (Philippians 1:23); we are of good courage, and we would rather be away from the body and at home with the Lord (2 Corinthians 5:8).

   Second, the intentions of the persecutors and the saints are different in the phrase, and lead you where you do not want. Third, we see that we should be prepared to suffer, but not to kill ourselves. Thus Christ says, you will stretch forth your hands. This was clearly the case with Peter, for when the people wanted to rebel against Nero and deliver him, he forbade it: Christ also suffered for you, leaving you an example (1 Peter 2:21).

5. The words another will gird you rightly come before and lead you. The thought is that another will gird you precisely because he will lead you where you do not want to go. So that no one would think this statement was written lightly, it should be noted that it was written after Peter’s death. Peter was killed during Nero’s lifetime, and John wrote this Gospel after he returned from the exile to which he had been banished during the reign of Domitian, with several other emperors reigning between Nero and Domitian.

6. John mentions this as something in the future, saying, he said this to signify by what death he was to glorify God, for the death of the saints gives glory to Christ: Christ will be honored in my body, whether by life or by death (Philippians 1:20); but let none of you suffer as a murderer, or a thief . . . yet if one suffers as a Christian, let him not be ashamed, but under that name let him glorify God (1 Peter 4:15). Indeed, the greatness of the Lord is shown by the fact that the saints brave death for His truth and faith.