The Renaissance genre of organological treatises inventoried the forms and functions of musical instruments. This article proposes an update and expansion of the organological tradition, examining the discourses and practices surrounding both musical and scientifi c instruments. Drawing on examples from many periods and genres, we aim to capture instruments’ diverse ways of life. To that end we propose and describe a comparative “ethics of instruments”: an analysis of instruments’ material configurations, social and institutional locations, degrees of freedom, and teleologies. This perspective makes it possible to trace the intersecting and at times divergent histories of science and music: their shared material practices, aesthetic commitments, and attitudes toward technology, as well as their impact on understandings of human agency and the order of nature.