For the Feast of St. Peter & St. Paul

"But if the good Shepherd, who laid down His life for His sheep, has raised up so many martyrs for Himself out of the very sheep, how much more ought those to contend to death for the truth, and even to blood against sin, who are entrusted by Him with the feeding, that is, with the teaching and the governing of these very sheep? And on this account, along with the preceding example of His own passion, who can fail to see that the shepherds ought all the more to set themselves closely to imitate the Shepherd, if He was so imitated even by many of the sheep under whom, as the one Shepherd and in the one flock she shepherds themselves are likewise sheep? For He made all those His sheep for [all of] whom He died, because He Himself also became a sheep that He might suffer for all."

St Augustine, On the Gospel of St. John, tractate CXXIII