Throughout the early modern period, the vast majority of natural philosophers remained deeply invested in exploring the meaning of ancient philosophical texts—there was no anti-humanist turn initiated by Descartes. Discussion of ancient philosophy was used, above all, in a genealogical manner, to shed light on the historical origins of doctrinal or methodological error. Accordingly, calls for a “return” to the philosophy of the presocratics, of Hippocrates, etc., should not be understood as simplistic recourse to authority, but rather as historico-methodological arguments about the disciplinary identity of natural philosophy. Indeed, natural-philosophical innovators were often more sure of what they stood against than what exactly they stood for. Seen from this perspective, the “philosophy of the Scientific Revolution” was an anti-philosophy, driven primarily by the colonization of the discipline by physicians on the one hand and mixed mathematicians on the other; the two groups eventually coming to work in tandem to squeeze out anything that looked like metaphysical physics.

Sidereus Nuncius was a seminal text of the Scientific Revolution. It reported celestial observations whose implications upended the geocentric cosmology few had ever doubted. But Galileo’s treatise also combined topics and methodologies that traditionally had been assigned separately to mixed mathematics and natural philosophy. Whereas the bounds between these disciplines had been weakened by earlier controversies, particularly about the regressus method and about the certainty of mathematics (i.e., the Quaestio de Certitudine), Sidereus Nuncius broke them down altogether, to the delight and dismay of readers. Galileo’s application of mathematical methods—empiricism and quantification—to natural philosophy framed the ensuing discussions, such that even those who disagreed with his conclusions responded on those grounds. Thus, the book was pivotal in the process of disciplinary admixture that reorganized the study of nature into modern science.