"Come down, Peter. You were eager to go on resting on the mountain; come down, preach the word, press on in season, out of season, censure, exhort, rebuke in all long-suffering and teaching. Toil away, sweat it out, suffer some tortures, so that by means of the brightness and beauty of right and good activity, you may come to possess in charity what is to be understood by the Lord's white garments. We heard the praises of charity, you see, when the apostle was being read: It does not seek its own advantage. It does not seek it own advantage, because it gives away what it possesses.
"Peter didn't understand this yet, when he was eager to live with Christ on the mountain. He was keeping that for you, Peter, after death. But now he himself says to you, 'Go down to labor on earth, to serve on earth, to be despised, crucified on earth.' Life came down, to be killed; bread came down, to go hungry; the way came down, to grow weary on a journey; the fountain came down, to experience thirst; and are you refusing to endure toil? Don't seek your own profit. Have charity and love, preach the truth; then you will arrive at eternity, where you will find security."
Augustine of Hippo, Sermon 78, 2.3-6