SILVESTER II, POPE.
He reigned from 2 Apr. 999 to 12 May 1003. Probably a native of Auvergne, Gerbert entered as a monk in the Benedictine abbey of St-Géraud d'Aurillac (Cantal). Borrel, Count of Barcelona, appreciated his learning and took him to Catalonia around 967. Atto, Bishop of Vich, introduced him to mathematical studies. The young monk made such progress that his protector presented him as a celebrity at the court of Otto I, who was then in Rome (970). He did not settle in that city but went to Reims, where a school of dialectics was flourishing (972).
Having become a master in this discipline, he taught with great renown; this earned him the title of scholasticus and the favor of Archbishop Adalbero. Otto II, who was present at a philosophical disputation with the German Otrik of Magdeburg at Ravenna—reported by the monk Richer—rewarded him by granting him the abbey of Bobbio (980). Political events in Italy forced him to resume teaching at Reims in 983.
Two treatises remain regarding the philosophical doctrines of S.: *De rationali et ratione* and *De Corpore et Sanguine Domini*. It is uncertain whether he actually adhered to the exaggerated realism suggested by some texts (cf. *De Corp. et Sang. Dom.*: PL 139, 189 B.). Besides his teaching of dialectics, Gerbert was renowned for his knowledge of geometry and astronomy. The construction of a celestial globe allowed him to explain to his listeners the movements of the stars and planets in a new way. The invention of a device that marked the time at night caused a sensation because until then only sundials had been used. Gerbert simplified the art of calculation and composed the first thirteen chapters of a treatise *De Geometria* (PL 139, 95–152 and the ed. by N. Bubnov, *Gerberti opera mathematica*, Berlin 1899).
Gerbert also occupies a distinguished place in the art of letter-writing. As secretary to Archbishop Adalbero, he maintained an intense diplomatic correspondence with his contemporaries and worked effectively for the rise of Hugh Capet. Julien Havet prepared a critical edition of the correspondence (Paris 1889) and succeeded in dating it and deciphering the enigmatic tachygraphic notes he employed; however, M. J. Lair (*Études critiques sur quelques textes des Xe et XIe siècles*, 2 vols., Paris 1899) proposed some corrections.
Thus, as a scientist and a man of letters, Gerbert exercised considerable influence in the 10th century. Politics brought him tribulations. After contributing to the success of Hugh Capet and the elimination of Charles of Lorraine, he might have aspired to the see of Reims following the death of Adalbero (23 Jan. 989), but Capet preferred Arnulf, who betrayed him and facilitated Charles of Lorraine’s entry into Reims. The king wished to punish the traitor and secure his deposition. Having received no satisfaction from Pope John XV, he convened a council at Saint-Basle de Verzy (June 991) where Arnulf, Bishop of Orléans, on the basis of arguments supplied by Gerbert, advanced a delicate thesis according to which the Gallican episcopate possessed the necessary qualities to take a decision (v. the procès-verbal drawn up in 995 by Gerbert himself: PL 139, 287–88 and in MGH, *Script.*, III, pp. 658–86). After Arnulf’s deposition and degradation, Gerbert was elected Archbishop of Reims. John XV would not tolerate the affront to his authority. When two convocations of the Gallican clergy to a council to be held at Aix-la-Chapelle or Rome proved ineffective, he threatened reprisals. An assembly of the Gallican clergy held at Chelles dared to confirm the sanctions against Arnulf and the election of Gerbert. Nevertheless, he appeared at the Council of Mouzon-sur-Meuse convened by the legate Leo and delivered a skillful defense (June 995). Later, before another council, he delivered a speech of which the text is still extant: PL 139, 345–50. No decision was reached, but Gerbert could no longer reside in Reims; he joined (996) the entourage of Otto III, who was visiting Italy, then went again to France where he attended the synod that opened in March 997 at Saint-Denis. Returning to the emperor’s court, through his influence he obtained the see of Ravenna. A profound change came over him: from a supporter of distinctly Gallican theories, as he had previously been, he became a zealous defender of the omnipotence of the Holy See. On 2 Apr. 999 the emperor presented him with the tiara.
S. II presented himself as an intrepid defender of papal authority and as a reformer of ecclesiastical morals. At first he allowed Arnulf, his adversary of Reims, to exercise episcopal functions, then he set himself to combat an evil that unfortunately raged in the Church: simony (PL 139, col. 169, which contains a *Sermo de informatione episcoporum*, the authenticity of which remains doubtful). The principal merit of S. II was to have maintained his freedom of action while at Rome the visionary Otto III sought to exercise his imperial prerogatives in the most rigorous manner. He particularly displayed the skill to secure recognition of papal authority in certain countries evangelized by missionaries of exclusively German origin. It was he who established two metropolitan sees in Hungary, at Esztergom and Kalocsa, and prepared the establishment in Poland of an independent ecclesiastical hierarchy. Having become pope by the will of Otto III, S. II felt far from secure in Rome. In February 1001 he had to flee the city under imperial protection. That year he is almost constantly found at the sovereign’s court, and his itinerary tends to merge with that of the emperor. The death of Otto III (23 Jan. 1002) might have been fatal to him. He returned to Rome and accommodated himself to a political regime in which the patrician John Crescentius left him scant powers. He died on 12 May 1003.
Gerbert had enemies and was the victim of Italian nationalists who could not tolerate the imperial enterprise. The *Liber pontificalis* (II, p. 263) contains a legendary account that represents the pope as an astrologer and a necromancer and attributes his honorable career to a pact made with the devil.
His works have been printed by Migne (PL 139) and by A. Olleris (*Œuvres de Gerbert*, Paris 1867).