Introduction

Jean-Baptiste Morin (1583–1656) was professor of mathematics at the Collège de France from 1629 until his death, and his interests included physics and astronomy as well as mathematics. A year after the condemnation of Galileo by the Inquisition in 1633, he published Pro telluris quiete, defending the traditional doctrine of the immobility of the Earth. Descartes read this, and also Morin's Quod Deus sit, which appeared the following year. This short work, constructed on Euclidean principles, with Definitions, Axioms, and Theorems, illustrates a way of doing metaphysics to which many were attracted about this time; Descartes himself offered a brief example of the genre (in his Replies to the Second Set of Objections), and its most celebrated later exponent was Spinoza. The project of establishing God's existence using the kind of self-evident reasoning characteristic of geometry clearly appealed to Descartes, but he recorded his disappointment with Morin's work in a letter to Mersenne written shortly before the publication of his own Meditations: