“Peter is called the Rock because, **like an immovable rock, he sustains and joins the mass of the entire Christian edifice.” (**Ambrose, Sermon 4).
“Christ is the Rock, 'For they drank from that spiritual Rock that followed them and that Rock was Christ, ’ and He did not refuse to bestow the favor of this title even upon His disciple, so that he too might be ‘Peter,’ in that he has from the Rock a solid consistancy of firm faith.” (Ambrose, Expos. in Luc.).
“[Christ] made answer: 'You are Peter, and upon this rock will I build my Church . . . ’ Could he not, then, strengthen the faith of the man to whom, acting on his own authority, he gave the kingdom, whom he called the rock, thereby declaring him to be the foundation of the Church [Matt. 16:18]?” (The Faith 4:5 [A.D. 379]).
“It is to Peter that he says: ‘You are Peter, and upon this rock I will build my Church’ [Matt. 16:18]. Where Peter is, there is the Church. And where the Church, no death is there, but life eternal” (Commentary on Twelve Psalms of David 40:30 [A.D. 389]).
St. Asterius of Pontus (387 A.D.):
"Peter went not away unrequited and unrewarded; but was declared “blessed” by the truly Blessed, and was called the Rock of faith, the foundation and substructure of the Church of God." (Ambrose, Hom. in Apost. Pet. et Paul, tom ii.).
St. John Chrysostom (387 A.D.):
“…and when I name Peter,** I name that unbroken Rock, that firm foundation**, the Great Apostle, the First of the disciples …” (Chrysostom, T. ii. Hom. iii. de Paednit).
“Peter, the leader of the choir, that Mouth of the rest of the Apostles, that Head of the brotherhood, that one set over the entire universe, **that Foundation of the Church.” (**Chrysostom, In illud. hoc Scitote).
"Peter, … that Pillar of the Church, the Buttress of the Faith, the Foundation of the Confession." (Chrysostom, T. iii. Hom. de Dec. Mill. Talent)
St. Jerome (393 A.D.):
"Christ is not alone in being the Rock, for He granted to the Apostle Peter that he should be called ‘Rock’. " (Jerome, Comm. on Jerimias 3:65).
“For what has Paul to do with Aristotle? Or Peter to do with Plato? For as the latter (Plato) was prince of philosophers, so was the former (Peter) prince of Apostles:** on him the Lord’s Church was firmly founded, and neither rushing flood nor storm can shake it.”** (Jerome, Against the Pelagians 1:14a).
“‘But,’ you [Jovinian] will say, ‘it was on Peter that the Church was founded’ [Matt. 16:18]. Well . . . one among the twelve is chosen to be their head **in order to remove any occasion for division.” **(Against Jovinian 1:26 [A.D. 393]).
“I follow no leader but Christ and join in communion with none but your blessedness [Pope Damasus I], that is, with the chair of Peter. I know that this is the rock on which the Church has been built. Whoever eats the Lamb outside this house is profane. Anyone who is not in the ark on Noah will perish when the flood prevails” (Letters 15:2 [A.D. 396]).
St. Augustine (410 A.D.):
“These miserable wretches, refusing to acknowledge the Rock as Peter and to believe that the Church has received the Keys to the Kingdom of Heaven, have lost these very keys from their own hands.” (Augustine, Christian Combat).
“…Why! a ****** that is cut from the vine retains its shape. But what use is that shape if it is not living from the root? Come, brother, if you wish to be engrafted in the vine. It is grievous when we see you thus lying cut off. Number the bishops from the See of Peter. And, in that order of fathers, see whom succeeded whom. This is the Rock which the proud gates of hades do not conquer. All who rejoice in peace, only judge truly.” --St. Augustine, Psalmus Contra Pertem Donati.