9 Not all bishops are bishops indeed. You consider Peter; mark Judas as well. You notice Stephen; look also on Nicolas, sentenced in the Apocalypse by the Lord's own lips, whose shameful imaginations gave rise to the heresy of the Nicolaitans. “Let a man examine himself and so let him come.” For it is not ecclesiastical rank that makes a man a Christian. The centurion Cornelius was still a heathen when he was cleansed by the gift of the Holy Spirit. Daniel was but a child when he judged the elders. Amos was stripping mulberry bushes when, in a moment, he was made a prophet. David was only a shepherd when he was chosen to be king. And the least of His disciples was the one whom Jesus loved the most.
My brother, sit down in the lower room, that when one less honorable comes you may be bidden to go up higher. Upon whom does the Lord rest but upon him that is lowly and of a contrite spirit, and that trembles at His word? To whom God has committed much, of him He will ask the more. “Mighty men shall be mightily tormented.” No man need pride himself in the day of judgment on merely physical chastity, for then shall men give account for every idle word, and the reviling of a brother shall be counted as the sin of murder. Paul and Peter now reign with Christ, and it is not easy to take the place of the one or to hold the office of the other.
There may come an angel to rend the veil of your temple, and to remove your candlestick out of its place. If you intend to build the tower, first count the cost. Salt that has lost its savor is good for nothing but to be cast out and to be trodden under foot of swine. If a monk fall, a priest shall intercede for him; but who shall intercede for a fallen priest?
Source: Letters (New Advent)