Peter the Venerable (Peter of Montboisser, b. 1092 or 1094), elected ninth abbot of Cluny in 1122, left behind a large collection of letters and polemical treatises. In his letters Peter expresses concern, among other issues, for the rigor and integrity of Benedictine life, as evidenced by repeated calls to avoid meat in the diet. At the same time he attempted to limit ascetic extremes—excesses in fasting, vigils, and acts of self-mortification—that might weaken the monk and prevent him from fulfilling his liturgical duties. He also was naturally concerned to protect and preserve Cluny’s properties. Letter 164, addressed...

I approach you, o jews—you, I say, who even to this day deny the Son of God. How long, wretches, will you fail to believe the truth? How long will you reject God? How long will you fail to soften [your] iron hearts? Behold that since antiquity almost the entire world has acknowledged Christ, while you alone do not acknowledge him; while all peoples submit to him, you alone do not listen to him; every tongue confesses him, while you alone deny him; others see him, hear him, understand him, but you alone remain blind, deaf, like stones. Clearly...

Listen then, O Jews, and know from your own Scriptures that Christ, or the Messiah as you would have it, is the Son of God. Come, then, propose your claims again in the first place to the most excellent of the prophets, Isaiah, and to a people, one neither from your time nor from ours, that believes the truth. Tell us what God said of the eternal generation of his Son: “Shall not I that make others to bring forth children, myself bring forth, said the Lord? Shall I, that give generation to others, be barren? said the Lord.”¹ What...

But after christ has been proved to be God and the Son of God on the authority of your texts, O Jews, perhaps, with your customary depravity, you will still insist and demand that his divinity be shown to you more clearly with other examples. And how, I ask, can it be shown more clearly? Among things of the world, what is clearer than the light, what is more resplendent than the sun? Nonetheless, even the light is a night for the blind, and the sun is darkness. The clarity of the sacred Scriptures shines so brightly on you, shines...

But because this can be enough for now concerning these matters, in the third part of the division mentioned above let the discussion (sermo) of divine wisdom proceed against another inspiration for your very foolish error, and in this part let it show you how foolish you are. Now, because you hear from the prophets that Christ is called a king, because you read in the Scriptures that he has a kingdom, you think that he will be a temporal king and that he will reign in time in the manner of David or Solomon, or of the other kings...

It remains for me to pursue a fourth and penultimate battle against you, O Jew, a battle in which (so I think) the one who conferred an easy palm of victory upon me in the earlier battles will do so once more. I will not be without the sword of Goliath to destroy you, as I hope to do if you do not want to live, a sword that I will use against you while you lie prostrate in your complete ruin, and I will cut off once again a blasphemous head with that blade’s edge with which you, girded...

It seems to me, O Jew, that with so many proof-texts and with so many arguments (rationes) I have satisfied every human being, I think, on those matters pertaining to the question proposed. But if I have satisfied every human being, then I have satisfied you too, if, nonetheless, you are human. In fact, I do not dare avow that you are human, lest perhaps I lie, because I recognize that that rational faculty that separates a human from the other animals or wild beasts and gives precedence over them is extinct or, rather, buried in you. Even your psalm...