John Cassian, 4th Century
— How could the Lord wish to be held onto for even a moment when in fact he does not even allow the spiritual sacrifices of our prayers to be offered if we know that someone else is angry with us? As he says: “If, then, you are offering your gift at the altar and there remember that your brother has something against you, leave your gift there at the altar, go first and be reconciled with your brother, and then come and offer your gift” (Matthew 5:23-24). How, then, are we permitted to be annoyed with our brother even until sundown — not to mention for several days — when, if he has something against us, we are not allowed to offer our prayers to God? We are commanded by the Apostle: “Pray without ceasing” (I Thessalonians 5:17). And: “In every place lifting up pure hands without anger and dissension” (I Timothy 2:8). It follows, therefore, that either we keep this kind of poison in our hearts and never pray, thus disobeying the apostolic and gospel precept by which we are commanded to pray ceaselessly and everywhere, or, if we deceive ourselves and dare to make prayer, contrary to his prohibition, we realize that it is not prayer that we are offering to the Lord but a stubborn and rebellious spirit.
— But why do we tarry for so long over gospel precepts and those of the Apostle when even the old law, which seems to be somewhat less demanding, warns of the very same thing? As it says: “you shall not hate your brother in your heart” (Leviticus 19:17). And again: “you shall not be mindful of the offense of your fellow citizens” (Leviticus 19:18). And again: “The ways of those who preserve the memory of a misdeed lead to death” (Proverbs 12:28). There as well you see that wickedness is checked not only in deed but even in secret thoughts, when not only hatred and vengefulness but even the recollection of an offense are commanded to be uprooted and cast out of the heart.
— Sometimes, when we have been overcome by pride or impatience and are unwilling to correct our unseemly and undisciplined behavior, we complain that we are in need of solitude, as if we would find the virtue of patience in a place where no one would bother us, and we excuse our negligence and the causes of our agitation by saying that they stem not from our own impatience but from our brothers’ faults. But, as long as we attribute our own wrongdoing to other people, we shall never be able to get near to patience and perfection.
— The sum total of our improvement and tranquility, then, must not be made to depend on someone else’s willing, which will never be subject to our sway; it comes, rather, under our own power. And so our not getting angry must derive not from someone else’s perfection but from our own virtue, which is achieved not by another person’s patience but by our own forbearance.
— A person may seem patient and humble to himself as long as he has nothing to do with anyone else, but he will soon revert to his former nature should some disturbing event occur. Indeed, vices that have lain hidden emerge at once there, and like unbridled horses nourished by a long period of quiescence they eagerly break out of their restraints, all the more violently and savagely endangering their charioteer. For when contact with other human beings ceases, along with the discipline that that provides, the vices grow wilder in us if they have not previously been purged, and through slothful security we lose even the pretense of patience that we gave the appearance of possessing at least for the sake of our brothers’ respect and our own good reputation when we lived among them.
— It should be known, however, that in those manuscripts where it reads: “Whoever is angry with his brother without cause shall be liable to judgment,” the phrase “without cause” is superfluous and was added by persons who did not think that anger needed to be cut off for a just cause, since in fact no one, however irrationally upset he was, would say that he had no cause for anger. It appear, therefore, that this was added by those who did not understand the intention of Scripture, which seeks to cut off completely the growth of anger and to maintain no occasion for indignation whatsoever lest, in ordering us to get angry with cause, an occasion for getting angry without cause also be offered us. For patience does not achieve its goal in righteous anger; it consists, rather, in not getting angry at all. I know, though, that the phrase “without cause” is interpreted in such a way as to mean that he is angered without cause who, when he is angry, is not allowed to seek revenge. Yet it is better to take it as it is found to be written both in many new manuscripts and in all the old ones.
— Hence it behooves the athlete of Christ, who is contending lawfully, to root out the movements of wrath. The perfect medicine for this disease is that we realize, first, that in no way are we permitted to get angry, whether for an unjust or a just cause, knowing that we shall at once lose the light of discretion and firm and correct counsel, as well as goodness itself and the restraints of righteousness, if the guiding principle of our heart is obscured by darkness; and then, that the purity of our mind will soon be driven out and that it can never become a temple of the Holy Spirit as long as the spirit of wrath dwells in us. Lastly, we should understand that we are never allowed to pray or to make petition to God when we are angry. Above all, we should keep before our eyes the uncertain state of our human condition, daily realizing that we shall depart from our bodies and that our chaste abstinence, the renunciation of all our property, the contempt of wealth, and the toil of fasting and keeping vigil will confer nothing on us if eternal punishment is being readied for us by the Judge of all on account of wrath and hatred alone.
1 John 3:11-15