Sethus Calvisius

Sethus Calvisius (1556 to 1615), also called Setho Calvisio and born Seth Kalwitz, was a German music theorist, composer, chronologer, astronomer and teacher of the late Renaissance. Born into a peasant family at Gorsleben in Thuringia, he earned his way through the start of a university career at Helmstedt by his musical talent and continued at Leipzig with the help of a patron. He directed the music school at Pforta from 1572 and from 1594 the same post at Leipzig, including the Thomanerchor at the Thomaskirche, which he kept until he died, refusing professorships of mathematics offered by Frankfurt and Wittenberg. As an astronomer he set out in his Opus Chronologicum of 1605 a system of dating based on the records of nearly three hundred eclipses, and in 1612 he put forward an ingenious but ineffective proposal for reforming the calendar. His book on music, Melodiae condendae ratio, appeared at Erfurt in 1592.