This dissertation reconstructs ways of thinking about, making music with, and listening to the organ in courtly Lutheran circles before the Thirty Years War through the music and writings of Michael Praetorius. The “instrument of instruments,” the organ represented man’s greatest musical achievement: a technological marvel that ordered sound itself, and human attempt to reach the music of the heavens. Praetorius, respected composer and theorist, and talented court organist, was both a brilliant practical musician and innovative thinker; in writing the history of the organ, he presented the musical instrument itself as a worthy subject for historical inquiry, promoting a radically modern notion of the organ as a site of musical, theological and scientific discovery. Praetorius inhabited a musical world in which the boundaries between vocal and instrumental styles were still undefined, with the latter much in the shadow of the human voice. I argue that in writing music about what he saw as the organ’s infinite potential, Praetorius began to construct music that was truly for the organ, exploring the possibility of its instrumental brilliance, expression and contrapuntal virtuosity, and writing idiomatic music specific to the organ itself, rather than general “instrumental” or “keyboard” music. I suggest that the organ’s unique instrumentality made it most suitable to evoke the unimaginable music of angels, in so doing forcing a reevaluation of what it meant to listen to instrumental music, and what value such music held, despite its textless nature.