1 Corinthians 15:5

Was seen of Cephas. Paul puts this appearance of Christ first, and therefore implies that the first man that Christ appeared to was Peter. I say "the first man," for He appeared to the Magdalene before S. Peter (S. Mar 16:9).

Then of the eleven. On the Sunday after the resurrection, when Thomas was now present, Christ appeared to the eleven, for the twelfth, Judas, had by that time hanged himself, or better still, "to the eleven," i.e., to the whole Apostolic College, which then had been reduced to eleven, Christ appeared on the day of His resurrection, though Thomas was absent. The Greek copies have, "then of the twelve." S. Augustine has the same reading (Quæst. Evangel lib. i. qu. 117), and he says there that, though Judas was dead, "the twelve" were still so called as by a corporate name. So the Decemvirs are said to assemble if only seven or eight are present. Chrysostom explains it otherwise. He says that Christ appeared to the twelfth, Matthias, after His ascension. But this is not recorded anywhere, and Paul is here naming the appearances of Christ before His ascension only. Ver. 6. After that He was seen of above five hundred brethren. The Greek word for above means (a) "more than," (b) "from heaven." Chrysostom and Theophylact take it here in the latter sense. For Christ appeared, they say, not walking on the ground, but above their heads, as though descending from the sky; and He did this that He might show them that He had ascended as well as risen, and might confirm their faith in His ascension. Hence any one may gather that Chrysostom thought that this appearance of Christ took place after His Ascension; but still it is not true, nor is of necessity gathered from what Chrysostom says.

This appearance of Christ, whether on a higher spot, as if from heaven, or in the air, evidently was prior to His ascension; and this is the common opinion of doctors; for we read nowhere of any public appearance after His ascension.

Many suppose that this was the well-known appearance of Christ on a mountain in Galilee, which He had so many times promised. All His disciples met there, as He had bidden. This was not at His ascension, but before it; for Christ ascended into heaven, not from Galilee, but from the Mount of Olives. See S. Jerome (ad Hedibiam, qu. 7).