The Desert Fathers are a wonderful source of inspiration, advice, guidance, and admonition. The following is from Abba Isaiah:
He also said, "When someone wishes to render evil for evil, he can injure his brother's soul even by a single nod of the head." (The Sayings of the Desert Fathers by Benedicta Ward, SLG, p. 70.)
We forget that we can harm others very easily. We forget that harming even those who seem to richly deserve it is wrong. In advice from the priest at my most recent confession, he reminded me that in a situation I had confessed that I had fulfilled justice but that as Christians we are also called to fulfill mercy. The problem is, to quote Clint Eastwood from the movie, Unforgiven, "We all got it comin' to us." The Good News is that if we sincerely seek it, what we will have coming to us is mercy. The bad news is that if we show no mercy, we will receive no mercy:
"...forgive, and you will be forgiven; give, and it will be given to you; good measure, pressed down, shaken together, running over, will be put into your lap. For the measure you give will be the measure you get back" (Luke 6:38).