Augustine on the Primacy of Peter
"Number the bishops even from the very seat of Peter, and see every succession in that line of fathers; that seat is the rock against which the proud gates of hell do not prevail." Psalmus Contra Partem Donati 43.30.
"There are many things which which most justly keep me in the bosom of the Catholic Church; the agreement of peoples and nations keep me; the authority established by miracles, fostered by hope, increased by charity, and confirmed by antiquity, keeps me; the succession of priests from the very See of the Apostle Peter, unto whom our Lord after His Resurrection committed His sheep to be fed, down to the Episcopate, to this day, keeps me; in fine, the very name of Catholic keeps me, which, not without cause, has in the midst of so many heresies clung to this Church alone in such a way that though all heretics want to be called Catholics, still when a stranger asks to be directed to the Catholic Church no man of them dares to point out his own basilica or house." Against the Letter of Manichaeus