Thomas a Kempis, The Imitation of Christ 2.3

Of the good, peaceable man

1. First keep yourself in peace, and then shall you be able to be a peacemaker towards others. A peaceable man does more good than a well-learned man. A passionate man turns even good into evil and easily believes evil; a good, peaceable man converts all things into good. He who dwells in peace is suspicious of none, but he who is discontented and restless is tossed with many suspicions, and is neither quiet himself nor suffers others to be quiet. He often says what he ought not to say, and omits what it were more expedient for him to do. He considers to what duties others are bound, and neglects those to which he is bound himself. Therefore be zealous first over yourself, and then may you righteously be zealous concerning your neighbor.

2. You know well how to excuse and to color your own deeds, but you will not accept the excuses of others. It would be more just to accuse yourself and excuse your brother. If you will that others bear with you, bear you with others. Behold how far you are as yet from the true charity and humility which knows not how to be angry or indignant against any save self alone. It is no great thing to mingle with the good and the meek, for this is naturally pleasing to all, and every one of us willingly enjoys peace and likes best those who think with us: but to be able to live peaceably with the hard and perverse, or with the disorderly, or those who oppose us, this is a great grace and a thing much to be commended and most worthy of a man.

3. There are those who keep themselves in peace and keep peace also with others, and there are those who neither have peace nor suffer others to have peace; they are troublesome to others, but always more troublesome to themselves. And there are those who hold themselves in peace, and study to bring others unto peace; nevertheless, all our peace in this sad life lies in humble suffering rather than in not feeling adversities. He who best knows how to suffer shall possess the most peace; that man is conqueror of himself and lord of the world, the friend of Christ, and the inheritor of heaven.