JOHN XXI, POPE

Pontificate: Sept. 16, 1276, to May 20, 1277; b. Petrus Juliani or Petrus Hispanus, Lisbon, Portugal, before c. 1205; d. Viterbo, Italy. Little is known about Peter. His short tenure as pope has made it virtually impossible to assess the impact of his reign. The two major tasks of his papacy, the restoration of the Eastern Church to the Western Church and a crusade, were incomplete at the time of his death. By contrast, Peter's work in the academic arena is much better known. Peter himself was an energetic man who made significant contributions in the fields of philosophy, theology, medicine, and logic. He is particularly remembered in the history of philosophy for his ordering of an investigation into the teaching of Averroism at the University of Paris. The action ultimately culminated in the condemnations of 1277.

There is virtually no information regarding Peter's early life. The currently accepted theory is that he was born before 1205, although scholars have suggested later dates. There is consensus, however, that Peter was born in Lisbon, Portugal, that he was the son of a man named Julianus, that he was baptized Peter Juliani and that he was probably tied to a noble family. In terms of his academic formation, Peter probably attended the cathedral school in Lisbon and by 1220 he was studying at the University of Paris. His teachers in theology were more likely Alexander of Hales, William of Auxerre, and William of Auvergne. By 1231 it would appear that Peter had traveled to northern Spain where he taught logic and composed a famous logical treatise that was entitled Tractatus. In 1235, Peter was probably studying medicine in both Toulouse and Montpellier.

By Jan. 11, 1245, Peter was in Siena, Italy where he taught medicine. He remained there for roughly five years and then he likely returned to Portugal. While there, Peter served as the dean of the Church of Lisbon and as archdeacon of Vermoim in the diocese of Braga. In March 1254, Peter attended the Cortes (Diet) of Leiria and in 1257 he was given the office of prior of Santa Maria at Guimarães. In 1263, Peter had been appointed magister scholarum of the Cathedral School of Lisbon. His activities between the years 1264–1272 are not known. In 1272 Pope Gregory X summoned Peter to become his court physician at Viterbo. It was during this period that Peter probably compiled his medical treatise Thesaurus pauperum. By the end of March or in early April 1273, Peter was selected to be the archbishop of Braga and on June 5 of that same year Pope Gregory X appointed him cardinal-bishop of Frascati (Tusculum). In June 1273, Peter accompanied Gregory to the General Council of Lyons in June 1273.

There is some evidence that suggests that that Peter returned to the University of Paris for a short stay in 1274. Nevertheless, he continued to govern the See of Braga until May 23, 1275. Peter's friend and patron Pope Gregory X died on Jan. 10, 1276. Gregory was succeeded by the remarkably short reigns of Innocent V and Adrian V and after the latter's death, Peter was elected pope. On Sept. 13, 1276 Peter was mistakenly crowned John XXI instead of XX. His reign as pope is commonly viewed as a political compromise between French and Italian factions. His most important deeds were the issuance of the bull Relatio nimis implacida in which he ordered the bishop of Paris, Étienne Tempier, to investigate errors being taught at the University of Paris. The bull led to attacks on Latin Averroism, a few positions regarding courtly love by Andrew Campellanus, and some ideas relating to St. Thomas' thought. In a second bull, Flumen aque vive, John ordered Bishop Tempier to purify the doctrines of the Parisian masters. John's pontificate ended abruptly when the roof of his study collapsed on him on May 14, 1277. He died from his injuries on May 20, 1277.

Peter was an able scholar and on one occasion he referred to himself as "doctor in liberal arts, rector of the philosophical sublimity, honor of the medical faculty and past master in the science of the soul." The description is apt but there are questions concerning the authorship of his Summulae logicales. According to one tradition of scholarship the work may have been written by a Dominican friar named Peter Alfonsi of Spain. The more popular view, however, is that the man who became Pope John XXI was the author of the Summulae logicales which is more properly called Tractatus. In addition to the Tractatus, Peter probably wrote a second logical treatise titled Syncategoremata. In the field of medicine, Peter's Thesaurus pauperum achieved great notoriety and has overshadowed his 14 other works on medicine that include commentaries on Hippocrates, Galen, and Isaac. As rector of philosophical sublimity, Peter is credited with having commented on Aristotle's De Anima, Historia animalium, De morte et vita, De causis longitudinis et brevitatis vitae, and De sensu et sensato. Apparently Peter wrote two commentaries on pseudo-Denys the Areopagite that reflect some influence from De coelesti hierarchia, Neoplationism, and St. Augustine. Finally, as a past master of the science of the soul, Peter argued for an Augustinian view of God's role in illuminating the intellect in ordinary cognition in his work Scientia libri de anima.

Bibliography: Soources. john xxi, Summulae logicales, ed. i. m. bocheŃski (Turin 1947) ; Tractatus, called afterwards Summule Logicales, ed. l.m. de rijk (Leiden 1972) ; Expositio librorum beati Dionysii, ed. m. alonso (Lisbon 1957) ; Scientia libri de anima, ed. id. (Madrid 1941) ; Comentario al "De anima" de Aristoteles, ed. id. (Madrid 1944) ; Expositio libri De anima. De morte et vita et De causis longitudinis et brevitatis vitae. Liber naturalis de rebus principalibus, ed. id. (Madrid 1952) ; Thesaurus pauperum, ed. and tr. l. de pina, and m. h. da rocha pereira (Oporto 1955) ; Regimen sanitatis, ed. m. h. da rocha pereira (Figueira da Foz 1960) ; Die Ophthalmologie: Liber de oculo, ed. and tr. a. m. berger (Munich 1899) ; Le Registre de Jean XXI, ed. l. cadier (Paris 1898) ; The Summulae logicales of Peter of Spain, ed. and tr. j. p. mullally (Notre Dame, Ind. 1945). Literature. r. stapper, Papst Johannes XXI (Münster 1898). l. thorndike, A History of Magic and Experimental Science (New York 1923–58) 2:488–516. m. grabmann, Handschriftliche Forschungen und Funde zu den philosophischen Schriften des Petrus Hispanus, Sitzungsberichte der Bayerischen Akademie der Wissenschaften zu München 9 (Munich 1936). j. ferreira, "As Sümulas logicais de Pedro Hispano e os seus comentadores, " Colectânea de Estudos 3 (1952) 360–393; "Introduçâo ao estudo do Liber de anima de Pedro Hispano, " Revista filosófica 3 (Coimbra 1954) 177–198; Presença do Augustinismo avicenizante na teoria dos intelectos de Pedro Hispano (Braga 1959) ; "L'Homme dans la doctrine de Pierre d'Espagne, " in L'Homme et son destin (Actes du Premier Congrès International de Philosophie médiévale; Louvain-Paris 1960) 445–461. l.m. de rijk, "On the Genuine Text of Peter of Spain's Summule Logicales I, " Vivarium 6 (1968) 1–34; "On the Genuine Text of Peter of Spain's Summule Logicales IV, " Vivarium 7 (1969) 120–162; "On the Life of Peter of Spain, the author of the Tractatus, called afterwards Summule Logicales " Vivarium 8 (1970) 123–154. m. de asua, "El Comentario de Pedro Hispano Sobre el De Animalibus. Transcripcion de las quaestiones sobre la controversia entre medicos y filosofos, " Patristica et mediaevalia 16 (1995) 45–66; a. d'ors "Petrus Hispanus O.P. Auctor Summularum, " Vivarium 35 no. 1 (1997) 21–71; m. de asua "Los Problemata o Quaestiones de animalibus de Pedro Hispano, " Stromata 54 (1998) 267–302

[j. a. sheppard]