Clavius, Christoph (1537-1612)

German mathematician and astronomer. Clavius entered the Jesuit order at Rome in 1555. In 1560, after strudying for a time at the Portuguese University of Coimbra in 1560, he began teaching mathematics a the Collegio Romano in Rome in 1565, remaining there for all but two of the next forty-seven years as professor of mathematics.

In 1574, he published his main work, Elements of Euclid. Clavius in his day acquired the reputation of being the "Euclid of the sixteenth century". His Elements was not a translation, but included notes collected from previous commentaries, as well as clarifications of his own. The first six books of Clavius' Elements was translated by Matteo Ricci with the help of Chinese scholars between 1603 and 1607.

As an astronomer, Clavius was a supporter of the Ptolomaic system and an opponent of Copernicus, whose theory he considered to not only physically absurd, but in contradction to many passages in the scriptures. Nevertheless, he became friends with twenty-three year-old Galileo, and remained so all his life. In a report tothe Holy Office in 1611, he confirmed Galileo's discoveries, but not his theory.

In his Epitome arithmeticae practicae (1583), he gave a notation for fractions, and explained how to find the lowest common multiple. In his Algebra (1608) he wrote the decimals in the form of common fractions. Algebra also iintroduced the German plus (+) and minus (-) signs into Italy ans made use of brackets. He uses symbols for unknown quantities, but did not take any notice of negative roots.

As his pupil, Ricci introduced his Arithmetic and his Elements into China, as well as his ptolemaic ideas. Chinese arithmetic at that time was performed with counting rods, and did not allow the recording of intermediary operations during lenghthy calculations, so that checking for an error requierd the whole sequence of operations to be repeated. They were consquently impressed by the pencil and paper methods of arithmetical calculation introduced by Ricci, since keeping a reocord of intermediary operations, made checking for errors so much easier. However, they saw the arithmetic problems studied as rather trivial. In the same way, like most modern schoolboys, they found the geometrical results in the Elements of Euclid, trivial, but were greatly impressed by the method of proof in which theorems were obtained by arguing logically from a set of axioms and postulates.

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Ths page last revised on the 25th September, 2002