Background
Clavius was born on March 25, 1538, in Bamberg, Germany. Little is known about Clavius' early life. His given name is not known to any great degree of certainty—it is thought by scholars to be perhaps Christoph Clau or Klau.
3004-531 Coimbra, Portugal
Clavius entered the Jesuit order at Rome in 1555 and later studied for a time at the University of Coimbra (Portugal), where he observed the eclipse of the sun on 21 August 1560.
Astronomer mathematician scientist
Clavius was born on March 25, 1538, in Bamberg, Germany. Little is known about Clavius' early life. His given name is not known to any great degree of certainty—it is thought by scholars to be perhaps Christoph Clau or Klau.
Clavius entered the Jesuit order at Rome in 1555 and later studied for a time at the University of Coimbra (Portugal), where he observed the eclipse of the sun on 21 August 1560.
Clavius began teaching mathematics at the Collegio Romano in Rome in 1565, while still a student in his third year of theology; and for all but two of the next forty-seven years he was a member of the faculty as professor of mathematics or as scriptor. From October 1595 until the end of 1596, he was stationed in Naples.
In 1574 Clavius published his main work, The Elements of Euclid. With the help of native scholars, Matteo Ricci, between 1603 and 1607, translated into Chinese the first six books of Clavius’ Elements. The Elements, which is not a translation, contains a vast quantity of notes collected from previous commentators and editors, as well as some good criticisms and elucidations of his own. Among other things, Clavius made a new attempt at proving the “postulate of parallels.” In his Elements of 1557, the French geometer Peletier held that the “angle of contact” was not an angle at all. Clavius was of a different opinion; but Viete, in his Variorum de rebus mathematicis responsorum of 1593, ranged himself on the side of Peletier. In a scholion to the twelfth proposition of the ninth book of Euclid, Clavius objects to Cardanus’ claim to originality in employing a method that derives a proposition by assuming the contradictory of the proposition to be proved. According to Clavius, Cardanus was anticipated in this method by Euclid and by Theodosius of Bithynia in the twelfth proposition of the first book of his Sphaericorum.
As an astronomer, Clavius was a supporter of the Ptolemaic system and an opponent of Copernicus. In his In Sphaeram Ioannis de Sacro Bosco commentarius (Rome, 1581) he was apparently the first to accuse Copernicus not only of having presented a physically absurd doctrine but also of having contradicted numerous scriptural passages. The friendship between Clavius and Galileo, according to their correspondence, began when Galileo was twenty-three and remained unimpaired throughout Clavius’ life. In a report of April 1611 to Cardinal Bellarmine of the Holy Office, Clavius and his colleagues confirmed Galileo’s discoveries, published in the Sidereus nuncius (1610), but they did not confirm Galileo’s theory. In his Epitome arithmeticaepracticae (Rome, 1583), Clavius gave a distinct notation for “fractions of fractional numbers,” but he did not use it in the ordinary multiplication of fractions. He offered an explanation for finding the lowest common multiple, which before him only Leonardo Fibonacci in his Liber abaci (1202) and Tartaglia in his General trattato di numeri et misure (1556) had done.
In his Astrolabium (Rome, 1593) Clavius gives a “tabula sinuum,” in which the proportional parts are separated from the integers by dots. However, his real grasp of that notation is open to doubt, and the more so because in his Algebra (Rome, 1608) he wrote all decimal fractions in the form of common fractions. Apart from that, his Algebra marks the appearance in Italy of the German plus ( + ) and minus ( - ) signs and of algebraic symbols used by Stifel. He was one of the very first to use parentheses to express aggregation of terms.
Mention must also be made of Clavius’ improvement of the Julian calendar. Pope Gregory XIII brought together a large number of mathematicians, astronomers, and prelates, who decided upon the adoption of the calendar proposed by Clavius, which was based on Reinhold’s Prussian Tables. To rectify the errors of the Julian calendar it was agreed to write in the new calendar 15 October immediately after 4 October of the year 1582. The Gregorian calendar met with a great deal of opposition from scientists such as Viéte and Scaliger and from the Protestants.
(Latin Edition)
1588(Latin Edition)
1609Jesuit scholars achieved great respect for their contributions to mathematical sciences, and Clavius was the architect of the mathematical curriculum in the Jesuit educational establishment. His influence on the Ratio studiorum, the plan of studies for Jesuit schools, published in final form in 1599, established mathematics as a vital component in an era when mathematical subjects were rarely or inconsistently taught in many institutions of higher learning. His concerns went beyond curriculum parameters and extended to measures intended to enhance the prestige of mathematical work and the respect accorded its specialists.
Quotes from others about the person
His contemporaries called Clavius “the Euclid of the sixteenth century.”