GUITMUND OF AVERSA. – Benedictine theologian, born in France at the beginning of the 11th century, died c. 1095. The details of his life are scanty and uncertain. A disciple of LANFRANC OF BEC, he became a monk at the abbey of La-Croix-Saint-Leufroy; he then probably went to England, invited by WILLIAM THE CONQUEROR, who may have proposed him as bishop for some see in the island and later for the metropolitan see of Rouen. After going to Rome, he became a fervent supporter of GREGORY VII, by whom he may have been created cardinal; he participated in the election of VICTOR II and under URBAN II he was certainly bishop of Aversa.
He wrote: *Confessio de sancta Trinitate, Christi humanitate Corporisque ac Sanguinis Domini nostri veritate* (PL 149, 1495-1502): a clear and concise exposition of the three Mysteries; *Epistola ad Erfastum* (ibid., 1501-58): here he treats of the Trinitarian Mystery, illustrated by the comparison of the solar orb, which diffuses light and heat. These two writings are, according to internal criticism, antecedent to the important work by which G.’s name is bound: *De corporis et sanguinis Domini veritate libri tres*, which, in its broad outlines, follows the development of BERENGAR OF TOURS’s *De sacra coena* (v.), against which it is directed. The first book opens with valuable information on the origin and ramifications of the Berengarian heresy and answers the questions posed by the interlocutor. The entire work is indeed conducted in the form of a dialogue between the author and Rogerio, who is perhaps the future abbot of Montebourg. The second book resolves the difficulties raised by Berengar; the third adduces positive proofs of the Catholic thesis, in opposition to the two Berengarian choices of the *umbrici* and the *impanatores*. The doctrine of this treatise is complete and, apart from some uncertainties regarding the fate of the species consumed by fire or gnawed by mice, is clear and precise; the demonstration proceeds securely, constantly appealing to Revelation and to the universal consensus of the Church. These qualities explain the fame which G. always enjoyed: even during his lifetime he was more renowned than St ANSELM OF AOSTA himself (Epistolarum lib. I, ep. 16: PL 158, 1082: «fama Lanfranci et Guitmundi plus mea per orbem volat»); Peter the Venerable judged his treatise inferior to that of ALGER OF LIÈGE (v.), but superior (melius, perfectius) to the book of LANFRANC (Adversus Praetorubianos: PL 189, 788); William of Malmesbury calls him «nostri temporis eloquentissimus» (Gesta regum Anglorum, III: PL 179, 1257). In the 16th century Erasmus edited the first edition of *De corporis... veritate* (Antwerp 1530) to oppose, together with the work of ALGER, the innovations of the Sacramentarians (Zwingli, Carlostadio, Œcolampadius), and for the same purpose it was reprinted by Johannes Ulimmer (Louvain 1561). Later included in the great patristic collections of Paris and Lyon, it passed into Migne (PL 149, 1427-94) and into Hurter (Sanctorum Patrum opuscula selecta, XXVIII, Innsbruck 1879).
Confused with Wittmund of St-Evroul or with Christian Druthmar (perhaps because he also bore the name Christianus), works of these authors were attributed to G. Orderic Vitalis makes him the author of an *Oratio ad Gnil-lelimum I Anglorum regem cum recusaret episcopatum* (PL 149, 1509-12), which is certainly a fabrication by the historian, who imitates Livy.