Pope Sylvester II
Pope Sylvester II, originally known as Gerbert of Aurillac, was a scholar and teacher who served as the bishop of Rome and ruled the Papal States from 999 to his death. He endorsed and promoted study of Moorish and Greco-Roman arithmetic, mathematics and astronomy, reintroducing to Western Christendom the abacus, armillary sphere, and water organ, which had been lost to Latin Europe since the fall of the Western Roman Empire. He is said to be the first in Christian Europe to introduce the decimal numeral system using the Hindu–Arabic numeral system.
Early life
Gerbert was born about 946, or at any rate between 945 and 950. His exact birthplace is unknown, but it must have been in what was then the Duchy of Aquitaine, part of the Kingdom of France. More precise proposals include the town of Belliac, near the present-day commune of Saint-Simon, Cantal, or Aurillac. Another speculated location is the province of Auvergne. Gerbert's parents, wanting him to have a quality education, took him to receive instruction at the nearby Benedictine Abbey. Here, Gerbert became a pupil of a monk named Raimund, who admired his desire of knowledge and assisted him in his studies.Around 963, he entered the Monastery of St. Gerald of Aurillac. In 967, Count Borrell II of Barcelona visited the monastery, and the abbot asked the count to take Gerbert with him so that the lad could study mathematics in Catalonia and acquire there some knowledge of Arabic learning. While away from the monastery, Gerbert pursued studies in Barcelona, and also received Arabic instruction at Seville and Córdoba.
Scholarly work
Gerbert studied under the direction of Bishop Atto of Vich, some 60 km north of Barcelona, and probably also at the nearby Monastery of Santa Maria de Ripoll. Like all Catalan monasteries, it contained manuscripts from Muslim Spain and especially from Córdoba, one of the intellectual centres of Europe at that time: the library of al-Hakam II, for example, had thousands of books. This is where Gerbert was introduced to mathematics and astronomy. Borrell II was facing major defeat from the Andalusian powers so he sent a delegation to Córdoba to request a truce. Bishop Atto was part of the delegation that met with al-Ḥakam II, who received him with honour. Gerbert was fascinated by the stories of the Mozarab Christian bishops and judges who dressed and talked like the Moors, well-versed in mathematics and natural sciences like the great teachers of the Islamic madrasahs. This sparked Gerbert's veneration for the Moors and his passion for mathematics and astronomy.Abacus and numerals
Gerbert learned of Hindu–Arabic digits and applied this knowledge to the abacus, but probably without the numeral zero. According to the 12th-century historian William of Malmesbury, Gerbert got the idea of the computing device of the abacus from a Moorish scholar from University of Al-Qarawiyyin. The abacus that Gerbert reintroduced into Europe had its length divided into 27 parts with 9 number symbols and 1,000 characters in all, crafted out of animal horn by a shieldmaker of Rheims. According to his pupil Richer, Gerbert could perform speedy calculations with his abacus that were extremely difficult for people in his day to think through using only Roman numerals. Due to Gerbert's reintroduction, the abacus became widely used in Europe once again during the 11th century.Bernelinus of Paris, who was probably a pupil of Gerbert, wrote a book called the Liber Abaci where he discussed the abacus' design. In this book, he individually introduced the "Hindu-Arabic" symbols the abacus used and related them to the more common Latin numerical nouns. Bernelinus' Liber Abaci has survived in 11 manuscripts from the 11th and 12th centuries. In two of them, probably the oldest ones, the number 3 is reproduced in a form that differs from the other manuscripts. This symbol is reminiscent of the "Tironian note" for the Latin word "ter" from the Roman shorthand. The reason for this is not known, but it is speculated that Bernelinus did not want to use an "unbeliever" symbol to indicate the number that represents the Holy Trinity.
Armillary sphere and sighting tube
Although lost to Europe since the terminus of the Greco-Roman era, Gerbert reintroduced the astronomical armillary sphere to Latin Europe via the Islamic civilization of Al-Andalus, which was at that time at the "cutting edge" of civilization. The details of Gerbert's armillary sphere are revealed in letters from Gerbert to his former student and monk Remi of Trèves and to his colleague Constantine, the abbot of Micy, as well as the accounts of his former student and French nobleman Richer, who served as a monk in Rheims. Richer stated that Gerbert discovered that stars coursed in an oblique direction across the night sky. Richer described Gerbert's use of the armillary sphere as a visual aid for teaching mathematics and astronomy in the classroom.Image:Sandro Botticelli 052.jpg|thumb|right|upright|An armillary sphere in a painting by Sandro Botticelli,
Historian Oscar G. Darlington asserts that Gerbert's division by 60 degrees instead of 360 allowed the lateral lines of his sphere to equal to six degrees. By this account, the polar circle on Gerbert's sphere was located at 54 degrees, several degrees off from the actual 66° 33'. His positioning of the Tropic of Cancer at 24 degree was nearly exact, while his positioning of the equator was correct by definition. Richer also revealed how Gerbert made the planets more easily observable in his armillary sphere:
Richer wrote about another of Gerbert's last armillary spheres, which had sighting tubes fixed on the axis of the hollow sphere that could observe the constellations, the forms of which he hung on iron and copper wires. This armillary sphere was also described by Gerbert in a letter to his colleague Constantine. Gerbert instructed Constantine that, if doubtful of the position of the pole star, he should fix the sighting tube of the armillary sphere into position to view the star he suspected was it, and if the star did not move out of sight, it was thus the pole star. Furthermore, Gerbert instructed Constantine that the north pole could be measured with the upper and lower sighting tubes, the Arctic Circle through another tube, the Tropic of Cancer through another tube, the equator through another tube, and the Tropic of Capricorn through another tube.
Scientific library
In late 984, Gerbert sent a letter to abbot Eberhard of Tours concerning the foundation of a large scientific library. He dedicated immense sums of money to establishing the library and purchasing texts from a wide variety of western European authors. He wrote to many monks and abbots in Europe requesting classical literature from their monasteries. Gerbert was also able to acquire some work from earlier era authors such as Cicero and Statius. Two specific requests Gerbert made that documentation exists for are letters sent to Lupitus of Barcelona and Bishop Miró Bonfill of Girona, asking the former for an astrology book and the latter for an arithmetic book. It can be inferred from this that the library contained many volumes of books covering a wide variety of topics, but the exact size and influence the library had is seemingly unknown.Ecclesiastical career
In 969, Borrell II made a pilgrimage to Rome, taking Gerbert with him. There Gerbert met Pope John XIII and Emperor Otto I. The pope persuaded Otto I to employ Gerbert as a tutor for his young son, Otto II. Some years later, Otto I gave Gerbert leave to study at the cathedral school of Rheims where he was soon appointed a teacher by Archbishop Adalberon in 973. He remained in this position until 989, with the only gap being his time as the head of the monastery of Bobbio from 981 to 983. When Otto II became sole emperor in 973, he appointed Gerbert the abbot of the monastery of Bobbio and also appointed him as count of the district, but the abbey had been ruined by previous abbots, and Gerbert soon returned to Rheims. After the death of Otto II in 983, Gerbert became involved in the politics of his time. In 985, with the support of his archbishop, he opposed King Lothair of France's attempt to take Lorraine from Emperor Otto III by supporting Hugh Capet. Hugh became king of France, ending the Carolingian line of kings in 987.Adalberon died on 23 January 989. Gerbert was a natural candidate for his succession, but King Hugh appointed Arnulf, an illegitimate son of King Lothair, instead. Arnulf was deposed in 991 for alleged treason against Hugh, and Gerbert was elected his successor. There was so much opposition to Gerbert's elevation to the See of Rheims, however, that Pope John XV sent a legate to France who temporarily suspended Gerbert from his episcopal office. Gerbert sought to show that this decree was unlawful, but a further synod in 995 declared Arnulf's deposition invalid. Gerbert then became the teacher of Otto III, and Pope Gregory V, Otto III's cousin, appointed him archbishop of Ravenna in 998.
With imperial support, Gerbert was elected to succeed Gregory V as pope in 999. Gerbert took the name of Sylvester II, alluding to Sylvester I, the advisor to Emperor Constantine I. Soon after he became pope, Sylvester II confirmed the position of his former rival Arnulf as archbishop of Rheims. As pope, he took energetic measures against the widespread practices of simony and concubinage among the clergy, maintaining that only capable men of spotless lives should be allowed to become bishops. In 1001, the Roman populace revolted, forcing Otto III and Sylvester II to flee to Ravenna. Otto III led two unsuccessful expeditions to regain control of the city and died on a third expedition in 1002. Sylvester II returned to Rome soon after the emperor's death, although the rebellious nobility remained in power, and he died a little later. Sylvester is buried in St. John Lateran.