This book is part of an ongoing project in which my aim is to understand how the process of shaping cognitive values around scientific ones began in the early modern era, and it is in many ways a companion to my Francis Bacon and the Transformation of Early Modern Philosophy (Cambridge, 2001). Descartes and Bacon are two of the founders of early modern thought, in many respects the founders of early modern thought. Both of them see natural philosophy as the core of the philosophical enterprise, by contrast, on the one hand, with Renaissance humanist philosophers, who saw moral and political philosophy in this role, and, on the other, with late Scholastic philosophers, who saw metaphysics as the core enterprise. They approach their task from different traditions – Bacon from the humanist tradition, and Descartes, at least in the Principia, from that of late Scholasticism – but both end up transforming not only natural–philosophical practice but the understanding of what it is to be a philosopher.

Earlier versions of material for the book have been presented at seminars and conferences at the Australian National University, the University of British Columbia, Eötvös University Budapest, the Universities of Chicago, Harvard, Helsinki, Hong Kong, Melbourne, and Ottawa, All Souls College Oxford, the State and Federal Universities of Rio de Janeiro, the Sorbonne, and the Universities of Sydney and Toronto. I am grateful to audiences at these events for some probing questions and fruitful discussion.