Jacques de Billy

For the English patristic scholar and Benedictine abbot, see Jacques de Billy (abbot) (1535–1581).

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 Pont-à-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. He died January 14, 1679 in Dijon, France.

Work and legacy

Jacques de Billy wrote multiple books on mathematics. In 1637, he published his first book called Abregé des Preceptes d’Algebre. This book helped teach basic principles and rules of algebra. In 1643, he published his second book called Nova Geometriae Clavis Alegrba, which was designed as a way to help solve geometric problems using algebra. French mathematician Bachet introduced Billy to indeterminate analysis at the Jesuit College at Rheims. Later on, in his time at the College of Dijon, Billy with the help of Pierre Fermat published his ideas on number theory. Billy's mathematical works also include Diophantus Redivivus. The foundational text for number theory was written in these volumes. Oldenburg and Rahn use this book as a reference to their own. Billy also wrote Diophantus Geometria Sive Opus Contextum ex Arithmetica et Geometrie Simul, which states a large number of solutions to algebraic equations, what we now call Diophantine equations.

In the field of astronomy, he published several astronomical tables. First published in Dijon by Pierre Palliot in 1656, Billy's tables of eclipses is called Tabulae Lodoicaeae seu universa eclipseon doctrina tabulis, praeceptis ac demonstrationibus explicata. Adiectus est calculus, aliquot eclipseon solis & lunae, quae proxime per totam Europam videbuntur. The tables were calculated for the years 1656 to 1693. This work also contains solar and lunar tables based on the Paris meridian. It also includes a detailed examination of problems involved in astronomical calculations. In 1665, Jacques de Billy wrote Discors de la comète qui a paru l'an 1665, au mois d'Auril. In this pamphlet, Billy talks about a comet observed in the sky in April of 1665. He talks about the path it took across the sky, its position to the stars and its appearance. He goes on to reject the common idea that comets were signs in the sky, and he states that they are actually a natural event that could be studied scientifically.

Jaques De Billy wrote the book Barlaam and Josaphat in 1692 which is a Greek hagiography, later leading to a Spanish translation by Antonio de Borja leading to a turning point in foreign literature in the Philippines, as well as the first book written there.

Billy put together a book called Doiphantus with Fermat’s Notes, from various of Fermat’s letters. This was a key role in making Fermat’s number-theoretic methods accessible to other mathematicians. In this book were several numerical problems that others were not able to solve.

Many other mathematicians such as Ozanam were influenced by many Jesuits, one of them being Jacques de Billy. Earlier in life, Billy wrote an analysis called Epilogue or Specious Analysis which was a book of mathematical problems that he didn’t revisit until later in his life after reading what Ozanam did in similar problems.

Billy was one of the first scientists to reject the role of astrology in science. He also rejected old notions about the malevolent influence of comets.

Jacques de Billy edited most Greek works in Latin, this was mainly due to his inability to find people who would publish his work.

In 1935, Jacques de Billy was honored with the naming of a lunar crater, which now bears the name Billy.

Works

• Diophanti redivivi (in Latin). Vol. 1. Lyon: Jean Thioly. 1670.
• Diophanti redivivi (in Latin). Vol. 2. Lyon: Jean Thioly. 1670.

See also

• List of Jesuit scientists
• List of Roman Catholic scientist-clerics

From the 1913 Catholic Encyclopedia

Jacques de Billy — (Billi)

A French patristic scholar, theologian, jurist, linguist, and a Benedictine abbot, b. 1535 at Guise in Picardy; d. 25 December, 1581 at Paris. 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 (Louis de Billy, of an old French family originally from Ile-de-France, and Marie de Brichanteau) gave him the opportunity he desired of pursuing unhampered his favourite study of letters. Quietly withdrawing to Lyons 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 Tourraine, 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 St.-Michel-en-l'Herme. After some hesitation de Billy accepted them, then entered the Order of St. Benedict, and later was made a regular abbot. Thenceforth he led a very ascetic life and governed his monasteries with great prudence. He was especially solicitous for the proper observance of monastic discipline and with that object in view renewed, in 1566, the statutes of his predecessor, Abbot Bertrand de Moussy. During the civil wars that devastated France at this period the monastery of St.-Michel-en-l'Herme was wholly destroyed. The abbot himself was frequently obliged to seek refuge from the ravages of war, and resided, for short periods, at Laon, Nantes, Paris, and in the Priory of Taussigny. The hardships he had to undergo in his journeyings, his incessant toil and study, and his ascetic observances gradually shattered his health, and while staying in Paris with his friend Gilbert Génébrard, he died at the comparatively early age of forty-six. He was buried in the choir of the church of Saint-Séverin.

From that day on which he entered the novitiate, de Billy set aside all profane studies and devoted himself exclusively to the study of the Fathers. His critical abilities and exceptional linguistic attainments (he wrote Greek and Latin with singular purity and precision) enabled him to do much for the emendation of the text and the correct interpretation of many obscure passages in the Church Fathers. His favourite among the Fathers was St. Gregory Nazianzen. His principal works are: (1) "S. Gregorii Nazianzeni opera omnia latine" (Paris, 1569); a second and better edition appeared in 1583. (2) "Consolations et instructions" (Paris, 1570). (3) "Récréations spirituelles" (Paris, 1573). (4) "S. Gregorii Nazianzeni opuscula" (Paris, 1575). (5) "Interpretatio Latina xviii priorum capitum S. Irenaei" (Paris, 1575). (6) "Antholigia sacra" (Paris, 1576). (7) "Joannis Damasceni opera" (Paris, 1577). (8) "Locutiones Graecae" (Paris, 1578). (9) "Opuscula aliqua S. Joannis Chrysostomi" (Paris, 1581). (10) "S. Isidori Pelusiotae epis. Libri tres" (Paris, 1585). (11) "S. Epiphanii opera" (Paris, 1612).

Ziegelbauer, Hist. rei lit. O. S. B. (Augsburg, 1754), III, 353; IV, 90, 99, 107; Niceron, Memoires, XXII, 187; Dom Prancois, Bibl. Gen. Des ecrivains de l'ordre de S. Benoit, (Bouillon, 1777), I, 126; Dupin, Nouv. Bibl. Des auteurs eccl. (Amsterdam, 1710), XVI, 123; Huet, De clar. Interpr., 261; Gallia Christiana (Paris, 1720), II, 1296, 1421; Natalis Alexander, Hist. Eccl. (Venice, 1771), XVII, 335; P.G., XXV, prol.

Bibliography

• O'Connor, John J; Robertson, Edmund F., "Jacques de Billy", MacTutor History of Mathematics Archive, University of St Andrews
• Moon Watch
• Polybiblio

Further reading

• Itard, Jean (1970–1980). "Billy, Jacques de". Dictionary of Scientific Biography. Vol. 2. New York: Charles Scribner's Sons. p. 131. ISBN 978-0-684-10114-9.