Mark 3:16

(de Con. Evan. ii. 17) But let no one suppose that Simon now received his name and was called Peter, for thus he would make Mark contrary to John, who relates that it had been long before said unto him, Thou shalt be called Cephas. (John 1:42) But Mark gives this account by way of recapitulation; for as he wished to give the names of the twelve Apostles, and was obliged to call him Peter, his object was to intimate briefly, that he was not called this originally, but that the Lord gave him that name.

(ubi sup.) And the reason that the Lord willed that he should at first be called otherwise, was that from the change itself of the name, a mystery might be conveyed to us. Peter then in Latin or in Greek means the same thing as Cephas in Hebrew, and in each language the name is drawn from a stone. Nor can it be doubted that is the rock of which Paul spoke, And this rock was Christ. (1 Cor. 10:4) For as Christ was the true light, and allowed also that the Apostles should be called the light of the world, (Matt. 5:14.) so also to Simon, who believed on the rock Christ, He gave the name of Rock.

Further, He gives the names of the Apostles, that the true Apostles might be known, so that men might avoid the false. And therefore it continues: And Simon he surnamed Cephas.

Thus from obedience, which Simon signifies, the ascent is made to knowledge, which is meant by Peter.