After Duke Heinrich Julius' death in 1613 Praetorius, though officially still attached to the new Duke at Wolfenbüttel, was invited to serve for two years at the court of Elector John Georg of Saxony, and he maintained a close relationship with the Saxony court even after the appointment ended. Indeed, from 1615 on, Praetorius spent more time away from Wolfenbüttel than he did attending to his duties as kapellmeister, and by 1620 Praetorius' frequent absence and poor health had caused so drastic a decline in the quality of music at Wolfenbüttel that he was dismissed from the position. He died just one year later, leaving his sizeable fortune to charity.
Praetorius' father and grandfather were both Lutheran theologians, and the composer inherited their deep religious sentiment, composing over 1,000 sacred compositions based on Protestant hymns and the Latin liturgy used in the Lutheran service. By comparison, only one small collection of secular compositions -- a group of instrumental dances -- survives. While such early works as Megalynodia Sionia, a collection of parody madrigals based on the music of Orlando di Lassus, among others, fail to display a real individuality of musical style. By the time of the Polyhymnia caduceatrix of 1619, Praetorius had embraced a remarkably forward-looking musical aesthetic in which the highly ornamented Italian vocal style of the times, and a dense scoring employing as many as 16 voices are all expressive possibilities at his disposal. Praetorius' Syntagma musicum, while never completed (the final section, intended to provide instruction in actual composition, remains missing), is one of the most important systematic compilations of early seventeenth century musical thinking.