 La Logique ou l’art de penser (Logic, or the Art of Thinking) is better known as the Port-Royal Logic (hereinafter Logic). It was one of the most influential pieces of philosophy written in the early modern period. This influence took two main forms. It was in many ways the most widely read text in formal logic from Aristotle to the end of the nineteenth century. It emphasized general principles of careful thinking over the memorization of complicated formal rules found in traditional texts. The result is a relatively compact work written in vernacular instead of the imposing Latin tomes otherwise available. Its readability is enhanced by long digressions devoted to moralizing and to recent advances in scientific understanding. As a result serious readers, “can read and understand in seven or eight days”, or so the authors claim (Logic, 13). It also served as a kind of handbook of some basic aspects of Cartesian and post-Cartesian science and philosophy.