4 Wherefore cease to worry me and to overwhelm me with your scrolls. Spare at least your money with which you hire secretaries and copyists, employing the same persons to write for you and to applaud you. Possibly their praise is due to the fact that they make a profit out of writing for you. If you wish to exercise your mind, hand yourself over to the teachers of grammar and rhetoric, learn logic, have yourself instructed in the schools of the philosophers; and when you have learned all these things you will perhaps begin to hold your tongue.
And yet I am acting foolishly in seeking teachers for one who is competent to teach everyone, and in trying to limit the utterance of one who does not know how to speak yet cannot remain silent. The old Greek proverb is quite true “A lyre is of no use to an ass.” For my part I imagine that even your name was given you out of contrariety. For your whole mind slumbers and you actually snore, so profound is the sleep— or rather the lethargy— in which you are plunged. In fact among the other blasphemies which with sacrilegious lips you have uttered you have dared to say that the mountain in Daniel out of which the stone was cut without hands is the devil, and that the stone is Christ, who having taken a body from Adam (whose sins had before connected him with the devil) is born of a virgin to separate mankind from the mountain, that is, from the devil.
Your tongue deserves to be cut out and torn into fragments. Can any true Christian explain this image of the devil instead of referring it to God the Father Almighty, or defile the ears of the whole world with so frightful an enormity? If your explanation has ever been accepted by any— I will not say Catholic but— heretic or heathen, let your words be regarded as pious. If on the other hand the Church of Christ has never yet heard of such an impiety, and if yours has been the first mouth through which he who once said “I will be like the Most High” has declared that he is the mountain spoken of by Daniel, then repent, put on sackcloth and ashes, and with fast-flowing tears wash away your awful guilt; if so be that this impiety may be forgiven you, and, supposing Origen's heresy to be true, that you may obtain pardon when the devil himself shall obtain it, the devil who has never been convicted of greater blasphemy than that which he has uttered through you.
Your insult offered to myself I bear with patience: your impiety towards God I cannot bear. Accordingly I may seem to have been somewhat more acrid in this latter part of my letter than I declared I would be at the outset. Yet having once before repented and asked pardon of me, it is extremely foolish in you again to commit a sin for which you must anew do penance. May Christ give you grace to hear and to hold your peace, to understand and so to speak.
Source: Letters (New Advent)