GILBERTO della PORRÉE (Gilbertus Porretanus). — Scholastic philosopher and theologian, born at Poitiers in 1076, died there in 1154. He studied at Chartres, where he had Bernardo di Chartres as his teacher (not to be confused with Bernardo Silvestris or di Tours, chancellor of Chartres in 1156), and where he later taught and served as chancellor. He then taught at Paris, Giovanni di Salisbury (v.) was among his pupils. In 1142 he was appointed bishop of Poitiers.
Under the humanistic influence of Chartres, he commented on the Opuscola sacra of Boethius, or rather on four of those opuscula (PL 64). He prefaced them with a prologue, not published by Migne, edited in part by Hauréau and subsequently in full by Grabmann (Die Gesch. der scholast. Methode, II, Fribourg in Br. 1912, pp. 417–19, note). In commenting on one of the Boethian opuscula, specifically the De Trinitate, G. encountered, in the very first chapter, the words « quare diversum etiam (come l'identico) vel genere vel specie vel numero dicitur. Sed numero differentiam accidentium varietas facit ». Inspired by these words of Boethius, who in turn was inspired by Porphyry, G. maintained that the universal is indeed in the individual, but is really distinct from the individuating principles (« accidentium varietas »), thus declaring himself for a realism apparently moderate but in reality exaggerated. In conformity with this ultra-realism of his, G. posited the three persons of the Holy Trinity as not only really distinct from one another but also from the divine nature or essence (Commento al II Opusc. di Boezio). This opinion was opposed by s. Bernardo di Chiaravalle and condemned in 1148 by the Council of Reims, in the presence of Pope Eugene III; it was subsequently repudiated by the author, who was obliged to acknowledge « neve Deus divina essentia diceretur ex sensu ablativi tantum sed etiam nominativi », as one of his admiring pupils, the historian Orrone di Frisinga, recorded (De gestis Friderici, I, I, cap. 56, in MGH, Scriptores, XX).
Another work by G. Porretano is the Liber sex principiorum (PL 188, 1257–70), on the last six Aristotelian categories, which Aristotle did not treat explicitly; it shows that G. was among the first in the twelfth century to introduce the « logica nuova », that is, the final books of Aristotle’s Organon, into the school of Chartres. The Liber sex principiorum, as a classical book, was honored with commentaries throughout the Middle Ages, alongside the books of Aristotle. s. Alberto Magno also commented on it, and Ermolao Barbaro adapted its Latin for the Venetian edition of 1496, subsequently reproduced in PL 188, 1257–70.
G. had followers and opponents in both philosophical and theological circles. Gioachino da Fiore, condemned for similar errors concerning the Holy Trinity at the Fourth Lateran Council in 1215, was also influenced by his works, directly or indirectly. Through the Sententiae divinitatis, which belong, if not to him, to his school, G. also influenced the Libri quatuor sententiarum of Pietro Lombardo. From S. Vittore, and specifically from Gualtiero di S. Vittore, almost G.’s contemporary, came the Contra quatuor labyrinthos Franciae, which depicted G. Porretano together with Abelardo, Pietro di Poitiers, and even Pietro Lombardo as equal dissolvers of traditional thought.
Other works by G.: Lettera to the abbot of S. Florent (PL. 188, 1255–58); Lettera to Bernardo di Chartres (L. Merlet, Lettres d'Yves de Chartres et d'autres personnages de son temps [Bibliothèque de l'École des Chartres, 4e serie, 1], Paris 1855, p. 461); Sermones super Canticum canticarum (Strasbourg 1497); Commento su l'Apocalisse (Paris 1512); Commento alle lettere di s. Paolo (unpublished: fragments in Revue d'histoire cccl., 13 [1912], pp. 677–683, notes); Commento ai Salmi (unpublished); Sententiae divinitatis (of G.’s school). In addition to the works, documents on G. are found in various sources (Mansi, XXI, cols. 712–736); Ottone di Frisinga, De gestis Friderici, I, 1, cap. 56 (MGH, Script., XX, p. 380 ff.); Gaufidus, Libellus contra Gillebertum (PL. 185, 595 ff.); B. Geyer, Die Sententiae Divinitatis, together with Book II of Gualtiero di S. Vittore’s Contra quatuor labyrinthos Franciae (Münster 1909); Johannes Sarscheriensis, Metalogicon, IV (ed. C. J. Webb, Oxford 1929); idem, Historia pontificalis (MGH, Script., XX, p. 524 ff.).