Pope Saint Clement I of Rome On Martyrs of Rome

To these men who spent their lives in the practice of holiness, there is to be added a great multitude of the elect, who, having through envy endured many indignities and tortures, furnished. us with a most excellent example. Through envy, those women, the Danaids and Dircae, being persecuted, after they had suffered terrible and unspeakable torments, finished the course of their faith with stedfastness, and though weak in body, received a noble reward. Envy has alienated wives from their husbands, and changed that saying of our father Adam, "This is now bone of my bones, and flesh of my flesh." Envy and strife have overthrown great cities and rooted up mighty nations.

These things, beloved, we write unto you, not merely to admonish you of your duty, but also to remind ourselves. For we are struggling on the same arena, and the same conflict is assigned to both of us. Wherefore let us give up vain and fruitless cares, and approach to the glorious and venerable rule of our holy calling. Let us attend to what is good, pleasing, and acceptable in the sight of Him who formed us. Let us look steadfastly to the blood of Christ, and see how precious that blood is to God, which, having been shed for our salvation, has set the grace of repentance before the whole world. 

-- Pope Saint Clement I of Rome from The First Epistle of Clement to the Corinthians