The Dioptrique, often translated as the Optics or, more literally, as the Dioptrics is one of Descartes’ earliest works. Likely begun in the mid to late 1620’s, Descartes refers to it by name in a letter to Mersenne of 25 November 1630 (AT I 182; CSM(K) III, 29). Its subject matter partially overlaps with Descartes’ more foundational project The World or Treatise on Light in which he offers a general mechanistic account of the universe including the formation, transmission, and reception of light. Although Galileo’s condemnation by the Church prompted Descartes to abandon, in 1633, his plans for publishing The World, he continued in the ensuing years to vigorously pursue a number of scientific projects, including projects related to his work in optics. He was eventually persuaded to publish three essays highlighting some of his discoveries together with an introductory essay concerning “the method for rightly directing one’s reason and searching for truth in the sciences” (AT VI 1; O 3). As one of those essays, Descartes’ Dioptrics finally appeared in print together with the Discourse on Method, the Meteorology and the Geometry in the summer of 1637 in a French language edition. It was republished in a Latin edition (without the Geometry) in 1644. The subject matter of the Dioptrics may be thought of as covering three main topics and is formally divided by Descartes into ten chapters or “discourses”. The first main topic concerns the nature of light and the laws of optics. In the first discourse, Descartes invites his readers to...