Various Excerpts from Dorotheos of Gaza :
Let us examine as to why a person sometimes gets annoyed when he hears an insult, and other times he endures it without getting agitated. What is the reason for this contrast? And is there one reason or are there several? There are several reasons, although they are all born from a main one. Sometimes it happens that after praying or completing a benevolent exercise, the person finds himself in a kind spiritual disposition and therefore, is amenable to his brother and doesn’t get annoyed over his words. It also happens that a person is partial to another, and as a consequence, endures without any annoyance, everything that the individual inflicts upon him. It also happens that a person may despise the individual who wants to insult him, and therefore ignores him.
+ + +
I will relate the following event. There was a novice living in the cloister with me and whom I have never seen annoyed or angry, even though he was plagued and insulted by many. This youth endured everything as though it wasn’t happening. Once I asked him to disclose to me the thought that he retains in his heart that makes him so patient. He responded with great contempt: "Why should I accept insults from them as I would from humans? After all — they are barking curs." Upon hearing this, I staggered away and thought: "Some path this brother had found!" Crossing myself, I departed, entreating God so that He would preserve him and me from such thoughts. And so it happens that one doesn’t get annoyed because he despises the insulter, and this is obvious perdition.
+ + +
People usually get annoyed either because they are in a bad mood, or they are nurturing unpleasant thoughts about another. However, the main reason for our annoyance is that we don’t reproach ourselves: this incurs spiritual disturbance and loss of inner peace. The true and genuine path toward a calm disposition is continual self-reproach. Even if a person had accomplished many good deeds yet doesn’t hold fast to the path of self-reproach, he will never cease being annoyed and insulting others, thereby losing the fruits of his good labor. In contrast, what joy and tranquility that person acquires who reproaches himself! Wherever he goes and whatever unpleasantness happens, or whatever insults he hears; he has convinced himself beforehand that he deserves all types of sorrows. That’s why when something unpleasant does happen, he doesn’t get annoyed. What more sorrowless condition can there be?