Wilhelm Seidel was the first to regard Johann Philipp Kirnberger’s reformulation of metre in Die Kunst des reinen Satzes in der Musik as a watershed moment in the history of music theory. As we consider Kirnberger’s innovation and importance in regard to his break with the past, we might examine more closely the conditions that made his re-imagining of metre possible. Kirnberger’s vital treatise participated in a broad epistemological shift in the conception of time. Changing metaphysical notions of time, along with technological developments such as the mechanical clock and the marine chronometer, helped to reshape a wider public’s notion of temporal passage. Alongside these developments, the nature of metre and tempo in music underwent continual revision. This article will explore the impact of shifting temporal conceptualizations on metre in the eighteenth century.