First, keep yourself at peace; then you can make peace among others. A peaceable person does more good than one very well educated. A hot-tempered person makes evil out of good; that kind of person believes the worst. But a good, peaceable person interprets everything to the good. Peaceable persons do not cultivate a critical attitude about others; but a discontented person tosses and turns with all sorts of criticism. Such critical people do not enjoy a quiet heart.
Thomas à Kempis, The Imitation of Christ, 2:3:1