Jacques de Billy (abbot)
Jacques de Billy (Billi) de Prunay was a French patristic scholar, theologian, jurist, linguist, and Benedictine abbot (1535—December 25, 1581).
Born in Guise in Picardy, he began his studies at Paris, completed a course of philosophy and theology before he was eighteen years of age, and then, at the request of his parents went to Orléans and later to Poitiers to study jurisprudence. But having no inclination for law, he devoted most of his time to literature. The early death of his parents gave him the opportunity he desired of pursuing unhampered his favorite study of letters.
Quietly withdrawing to Lyon and later to Avignon, de Billy devoted himself, for a period, entirely to the study of Greek and Hebrew. He already held in commendam the Abbey of St.-Léonard of Ferrières in Anjou, and the Priory of Taussigny in Touraine, when his older brother Jean, who had hitherto led a very worldly life, suddenly announced his intention of becoming a Carthusian, and resigned in favour of Jacques his two abbeys, Notre-Dame des Châtelliers and Saint-Michel-en-l'Herm.
Jacques de Billy
Jacques de Billy (March 18, 1602 – January 14, 1679) was a French Jesuit mathematician. Born in Compiègne, he subsequently entered the Society of Jesus. From 1629 to 1630, Billy taught mathematics at the Jesuit College at Pontà Mousson. He was still studying theology at this time. From 1631 to 1633, Billy taught mathematics at the Jesuit college at Rheims. From 1665 to 1668 he was professor of mathematics at the Jesuit college at Dijon. One of his pupils there was Jacques Ozanam. Billy also taught in Grenoble. He also served as rector of a number of Jesuit Colleges in Châlons-en-Champagne, Langres and in Sens.
The mathematician Claude Gaspard Bachet de Méziriac, who had been a pupil of Billy's at Rheims, became a close friend. Billy maintained a correspondence with the mathematician Pierre de Fermat.
Work and legacy
Billy produced a number of results in number theory which have been named after him. Bachet introduced Billy to indeterminate analysis. Billy's mathematical works include Diophantus Redivivus.
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