Gilbert of Poitiers (Gilbertus Porretanus)

GILBERT OF POITIERS (Gilbertus Porretanus). - Scholastic philosopher and theologian, b. at Poitiers in 1076, d. there in 1154. He studied at Chartres, where his master was Bernard of Chartres (not to be confused with Bernard Silvestris or of Tours, chancellor of Chartres in 1156), and where he later taught and was chancellor. He then taught at Paris, where he had as a pupil John of Salisbury (v.). In 1142 he was appointed bishop of Poitiers.

Under the humanistic influence of Chartres he commented on the Opuscula 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 then in full by Grabmann, (Die Gesch. der scholast. Methode, II, Freiburg im Br. 1912, pp. 417-19, note). G., commenting on one of the Boethian opuscula, namely the De Trinitate, encountered, right at the first chapter, the words « quare diversum etiam (like the identical) vel genere vel specie vel numero dicitur. Sed numero differentiam accidentium varietas facit ». Drawing inspiration from these words of Boethius, who in turn drew inspiration from Porphyry, G. affirms that the universal is indeed in the individual, but really distinct from the individuating principles (« accidentium varietas »), thus declaring himself in favor of a realism that is apparently moderate but in reality exaggerated. In conformity with this ultra-realism of his, G. posits the three persons of the Most Holy Trinity as not only really distinct from one another but also from the divine nature or essence (Commentary on the II Opusc. of Boethius). This opinion was opposed by St. Bernard of Clairvaux and condemned in 1148 by the Council of Reims, with Pope Eugene III present; 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, namely the historian Otto of Freising, left written (De gestis Friderici, I, I, chap. 56, in MGH, Scriptores, XX).

Another work of G. Porretanus is the Liber sex principiorum (PL 188, 1257-70) on the last six Aristotelian categories not expressly treated by Aristotle; from it, it emerges that G. was among the first in the 1100s to introduce the "new logic," that is, the last books of the Aristotelian Organon, into the school of Chartres. The Liber sex principiorum obtained, like a classic book, the honor of commentaries throughout the whole Middle Ages, alongside the books of Aristotle. St. Albert the Great also commented on it, and Ermolao Barbaro adapted its Latin, for the Venetian edition of 1496, later reproduced in PL 188, 1257-70.

G. had followers and adversaries in the philosophical field and in the theological field. Joachim of Fiore too was immediately or mediately affected by the influence of his works, condemned for similar errors concerning the Most Holy Trinity in the Fourth Lateran Council of 1215. G., through the Sententiae divinitatis, which belong, if not to him, to his school, also influenced the Libri quatuor sententiarum of Peter Lombard. From St. Victor, and precisely from Walter of St. Victor, almost a contemporary of G., came the Contra quatuor labyrinthos Franciae, depicting G. Porretanus along with Abelard, Peter of Poitiers and even Peter Lombard as so many destroyers of traditional thought.

Other works of G.: Letter to the abbot of St. Florent (PL. 188, 1255-58); Letter to Bernard of Chartres (L. Merlet, Lettres d'Yves de Chartres et d'autres personnages de son temps [Bibliothèque de l'École des Chartres, 4th series, 1], Paris 1855, p. 461); Sermones super Canticum canticarum (Strasbourg 1497); Commentary on the Apocalypse (Paris 1512); Commentary on the letters of St. Paul (unpublished: fragments in Revue d'histoire cccl., 13 [1912], pp. 677-683, notes); Commentary on the Psalms (unpublished); Sententiae divinitatis (of G.'s school). Besides the works, documents on G. are found in various sources (Mansi, XXI, coll. 712-736); Otto of Freising, De gestis Friderici, I, 1, chap. 56 (MGH, Script., XX, p. 380 ff.); Gaufidus, Libellus contra Gillebertum (PL. 185, 595 ff.); B. Geyer, Die Sententiae Divinitatis, with the II b. of Walter of St. Victor, Contra quatuor labyrinthos Franciae (Münster 1909); Johannes Sarscheriensis, Metalogicon, IV (ed. C. J. Webb, Oxford 1929); id., Historia pontificalis (MGH, Script., XX, p. 524 ff.).

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