Sethus Calvisius or Setho Calvisio, originally Seth Kalwitz (21 February 1556 – 24 November 1615), was a German music theorist, composer, chronologer, astronomer, and teacher of the late Renaissance.
He was born into a peasant family at Gorsleben in present-day Thuringia. By the exercise of his musical talents he earned money enough for the start, at Helmstedt, of a university career, which the aid of a wealthy patron enabled him to continue at Leipzig. He became director of the music-school at Pforta in 1572. In 1594 he was transferred to Leipzig in the same post, including directing the Thomanerchor at the Thomaskirche.[1] He retained this post until his death in Leipzig, despite the offers successively made to him of mathematical professorships at Frankfurt and Wittenberg.[2]
Calvisius was also a significant astronomer: in his Opus Chronologicum (Leipzig, 1605, 7th ed. 1685) he expounded a system based on the records of nearly 300 eclipses. An ingenious, though ineffective, proposal for the reform of the calendar was put forward in his Elenchus Calendarii Gregoriani (Frankfurt, 1612); and he published a book on music, Melodiae condendae ratio (Erfurt, 1592).[2] He composed choral pieces including Unser Leben währet siebzig Jahr.[1]
