Italian prelate; born at Ravenna 1007; died at Faenza 1072. About 1035 he entered the convent of Fonte Avellana near Gubbio, of which he became abbot. Together with Hildebrand, subsequently Pope Gregory VII., and Abbot Desiderius of Monte Casino, Damiani belonged to the most zealous champions of Church reform. In 1057 he was appointed Cardinal-Bishop of Ostia. At the instance of an Egyptian ecclesiastic, Honestus, he wrote two small controversial pamphlets to serve as a guide in religious disputations against the Jews, although he himself had no taste for such polemics.
In the first of these pamphlets, "Antilogus Contra Judæos," he sought, by means of numerous passages from the Old Testament, such as those relating to the Creation, the building of the Tower of Babel, the triple priestly benediction, the thrice-repeated "Holy," and the Messianic passages, to prove the Christian doctrines of the Trinity, the Messiah, and the divine sonship of Jesus. In the second, entitled "Dialogus Inter Judæum Requirentem et Christianum e Contrario Respondentem," he endeavored to refute—by claiming that all of the laws referred to are to be interpreted spiritually—the objection raised by the Jews that the Christians fail to observe the ceremonial law, although Jesus declared that he came to fulfil that law.
- S. Petri Damiani, Opera, in Migne's Patrologia, second series, 1853;
- cxlv., Neukirch, Das Leben des Petrus Damiani;
- Kleinermanns, Der Heilige Petrus Damiani;
- Vogelstein and Rieger, Gesch. der Juden in Rom, i. 267 et seq.