The name of René Descartes (1596–1650) is usually associated with the philosophical and scientific revolution of the seventeenth century. With his Meditations on First Philosophy (1641), Principles of Philosophy (1644) and other seminal texts, Descartes had a crucial role in dismantling the Aristotelian paradigm in philosophy, by opposing to it a mechanistic view of nature and a dualist theory of man. However, the ways in which his theories were disseminated and discussed are still to be fully ascertained, insofar as historians have so far privileged printed sources in their investigations. This project, on the other hand, will focus on handwritten documents testifying the reception of Descartes’s ideas in Europe. These sources include marginal notes to Cartesian printed texts, commentaries, and lecture notes, most of which still have to be retrieved and catalogued. By locating forgotten sources, providing an edition of a selection of them, and analysing their contents, this project is expected to shed light on a body of literature capable of deepening the comprehension of our philosophical past in a substantial way.