The book will contain four essays, all in French, with the general title of Project of a Universal science, capable of raising our nature to its highest perfection; also Dioptrics, Meteors and Geometry, wherein the most curious matters which the author could select as a proof of the universal science which he proposes are explained in such a way that even the unlearned may understand them.'
Fermat, Roberval and Desargues took exception in their various ways to the methods employed in the geometry, and to the demonstrations of the laws of refraction given in the Dioptrics and Meteors.
Besides the last two parts of the Principles of Philosophy, the physical writings of Descartes include the Dioptrics and Meteors, as well as passages in the letters.
His optical investigations are perhaps the subject in which he most contributed to the progress of science; and the lucidity of exposition which marks his Dioptrics stands conspicuous even amid the generally luminous style of his works.
About the same time also Mersenne sent to Descartes, as if they came from a friend in England, another set of objections which Hobbes had to offer on various points in the scientific treatises, especially the Dioptrics, appended by Descartes to his Discourse on Method in 1637; to which Descartes replied without suspecting the common authorship of the two sets.
Descartes, in his treatise on Dioptrics (1637), attributes the discovery to Metius "about thirty years ago," whilst Schyraelus de Rheita, a Capuchin friar, in his Oculus Enoch et Eliae (Antwerp, 1645), gives the credit to Lippershey about 1609.