from the book Institutes by St. John Cassian

BOOK VIII. OF THE SPIRIT OF ANGER. 

CHAPTER XI: Of those to whose wrath even the going down of the sun sets no limit.

BUT what am I to say of those (and I cannot say it without shame on my own part) to whose implacability even the going down of the sun sets no bound: but prolonging it for several days, and nourishing rancorous feelings against those against whom they have been excited, they say in words that they are not angry, but in fact and deed they show that they are extremely disturbed? For they do not speak to them pleasantly, nor address them with ordinary civility, and they think that they are not doing wrong m this, because they do not seek to avenge themselves for their upset. But since they either do not dare, or at any rate are not able to show their anger openly, and give place to it, they drive in, to their own detriment, the poison of anger, and secretly cherish it in their hearts, and silently feed on it in themselves; without shaking off by an effort of mind their sulky disposition, but digesting it as the days go by, and somewhat mitigating it after a while. 

CHAPTER XVI: How useless is the retirement of those who do not give up their bad manners. 

SOMETIMES when we have been overcome by pride or impatience, and we want to improve our rough and bearish manners, we complain that we require solitude, as if we should find the virtue of patience there where nobody provokes us: and we apologize for our carelessness, and say that the reason of our disturbance does not spring from our own impatience, but from the fault of our brethren. And while we lay the blame of our fault on others, we shall never be able to reach the goal of patience and perfection. 

CHAPTER XVIII: Of the zeal with which we should seek the desert, and of the things in which we make progress there.

For a man appears to himself to be patient and humble, just as long as he comes across nobody in intercourse; but he will presently revert to his former nature, whenever the chance of any sort of passion occurs: I mean that those faults will at once appear on the surface which were lying hid

CHAPTER XIX: An illustration to help in forming an opinion on those who are only patient when they are not tried by any one. 

And so in the case of men who are aiming at perfection, it is not enough not to be angry with men. For we recollect that when we were living in solitude a feeling of irritation would creep over us against our pen because it was too large or too small; against our penknife when it cut badly and with a blunt edge what we wanted cut; and against a flint if by chance when we were rather late and hurrying to the reading, a spark of fire flashed out, so that we could not remove and get rid of our perturbation of mind except by cursing the senseless matter, or at least the devil. Wherefore for a method of perfection it will not be of any use for there to be a dearth of men against whom our anger might be roused: since, if patience has not already been acquired, the feelings of passion which still dwell in our hearts can equally well spend themselves on dumb things and paltry objects, and not allow us to gain a continuous state of peacefulness, or to be free from our remaining faults: unless perhaps we think that some advantage and a sort of cure may be gained for our passion from the fact that inanimate and speechless things cannot possibly reply to our curses and rage, nor provoke our ungovernable temper to break out into a worse madness of passion. 

CHAPTER XXII: The remedies by which we can root out anger from our hearts. WHEREFORE the athlete of Christ who strives lawfully ought thoroughly to root out the feeling of wrath. And it will be a sure remedy for this disease, if in the first place we make up our mind that we ought never to be angry at all, whether for good or bad reasons: as we know that we shall at once lose the light of discernment, and the security of good counsel, and our very uprightness, and the temperate character of righteousness, if the main light of our heart has been darkened by its shadows: next, that the purity of our soul will presently be clouded, and that it cannot possibly be made a temple for the Holy Ghost while the spirit of anger resides in us; lastly, that we should consider that we ought never to pray, nor pour out our prayer to God, while we are angry. And above all, having before our eyes the uncertain condition of mankind, we should realize daily that we are soon to depart from the body, and that our continence and chastity, our renunciation of all our possessions, our contempt of wealth, our efforts in fastings and vigils will not help us at all, if solely on account of anger and hatred eternal punishments are awarded to us by the judge of the world.