Sethus Calvisius

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.

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.

[1] He retained this post until his death in Leipzig, despite the offers successively made to him of mathematical professorships at Frankfurt and Wittenberg.

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.