It was a custom...

…with the brothers of our God-loving and holy father Pachomius, to assemble every evening in an appointed place in the monastery to hear his teaching. Once, as they were assembled as usual to hear the great man, he commanded a certain Theodore, who had been in the monastery twenty years, to speak to the brothers. Straightway, without any disobedience, he spoke to them about things profitable to them. Some of the eldest brothers, when they saw what was happening, did not want to listen to him. They said within themselves, “He is a beginner and he is teaching us! We will not hear him.” They left the synaxis of the brothers and withdrew to their cells.’

When the brothers were dismissed from the instruction, the great man sent for and called those who had withdrawn. They came to the holy man and he asked them, “Why did you leave us and withdraw to your cells?” They said, “Because you have made a boy a teacher of us, a large group of old men and of other brothers.” When the great man heard this, he groaned and said, “Do you know from where evil first had its beginning in the world?” As they said, “From where?”, he replied and told them, “From pride, for which `the bright star dawning in the morning was dashed in pieces upon the ground,’ and for which also Nebuchanezzar, the king of Babylon, `dwelt among the wild beasts.’ (Is 14:12, Dn 5:21) Or have you not heard what is written, `The man with an arrogant heart is abhorrent to the Lord? For everyone who exalts himself will be humbled.’ (Pr.15:9, Lk 14:11) Now you have been despoiled by the devil of all your virtue, not knowing that pride is the mother of all evils. For it was not Theodore whom you left when you went away, but you fled from the word of God and you fell away from the Holy Spirit. Truly wretched are you, and worthy of all pity. How is it that you did not understand that it was Satan who was causing this in you, and because of this you have been separated from God? O what a great wonder! God humbled Himself and became obedient even unto death for your sake; and yet we, who are by nature lowly, puff ourselves up. The order is overthrown by us: He who is above all things and exceedingly great brought the world to Himself through His humility, when He could have burned it up by a mere glance! And we who are nothing make ourselves proud, not knowing that by this we are pushing ourselves into the depths of the earth.

Did you not see that I was standing and listening to his teaching? In truth I tell you, I profited greatly from listening to him. For it was not to test him that I enjoined him to speak to you, but because I expected to draw profit for myself. How much more then ought you to have heard his word with great eagerness and humility? Verily, I, your father in the Lord, was listening to him with all my soul as one who does not know his right from his left. Therefore, before God, I tell you that if you do not show great repentance for this error, and if you do not weep and mourn for yourselves so that what happened may be forgiven you, you will go to perdition.”

from the Paralipomena (Left-Overs) of the Greek life of St. Pachomius, chap. 1
St. Theodore the Sanctified, commemorated 16 May