John 21:18

To this command our Lord unexpectedly adds a reflection and warning emphasised by the usual ἀμὴν ἀμὴν λέγω σοι. It had been with a touch of pity Jesus had seen the impulsive, self-willed Peter gird his coat round him and plunge into the sea. It suggested to Him the severe trials by which this love must be tested, and what it would bring him to: ὅτε ἦς νεώτερος, “when thou wert younger” (the comparative used not in relation to the present, but to the γηράσης following) “thou girdedst thyself and walkedst whither thou wouldest,” i.e., your own will was your law, and you felt power to carry it out. The “girding,” though suggested by the scene, John 21:7, symbolises all vigorous preparation for arduous work. ὅταν δὲ γηράσης … θέλεις. The interpretation of these words must be governed by the succeeding clause, which informs us that by them Jesus hinted at the nature of Peter's death. But this does not prevent us from finding in them, primarily, an intimation of the helplessness of age, and its passiveness in the hands of others, in contrast to the self-regulating activity and confidence of youth. The language is dictated by the contrasted clause, and to find in each particular a detail of crucifixion, is to force a meaning into the words. ἐκτενεῖς τὰς χεῖρας σου is not the stretching out of the hands on the cross, but the helpless lifting up of the old man's hands to let another gird him. δοξάσει τὸν θεόν. “Magnificus martyrii titulus.” Grotius. “Die conventionelle Sprache der Märtyrerkirche klingt an in δοξ. τὸν θεόν; weil der Zeugentod zu Ehren Gottes erlitten wird.” Holtzmann. The expression has its root in John 12:23; John 12:28. καὶ τοῦτο … μοι. It is very tempting to refer this to John 13:36, ἀκολουθήσεις δὲ ὕστερον, and probably there is a latent reference to this, but in the first instance it is a summons to Peter to accompany Jesus as He retires from the rest. This is clear from what follows.