What causes winds was regarded as one of the most difficult questions of early modern natural philosophy. Vitruvius, the ancient Roman architectural author, put forth an alternative to Aristotle’s theory by likening the generation of wind to the actions of the aeolipile, which he believed made artificial winds. As Vitruvius’s work proliferated during the sixteenth and seventeenth centuries, numerous natural philosophers, including Descartes, used the aeolipile as a model for nature. Yet, interpretations of Vitruvius’s text and of the relation of the aeolipile to natural winds varied according to definitions and conceptions of air, wind, rarefaction, condensation, and vapor.