DESCARTES, René (1596–1650). [Opera philosophica…]. Amsterdam: Blaeu, 1685. 5 parts in 2 volumes, small 4to (191 x 146 mm). (Some minor browning or spotting). Half–title, engraved portrait frontispiece, Blaeu’s woodcut armillary device on title–pages, numerous in text woodcut illustrations, several full–page. Full early vellum, gilt–stamped spines. Seventh edition (“Editio Ultima”), comprising of Descartes philosophical works: Principia philosophiae; Specimena philosophiae; Passiones animae; Meditationes de prima philosphia; and Appendice continens obiectiones… “It is no exaggeration to say that Descartes was the first of modern philosophers and one of the first modern scientists; in both branches of learning his influence has been vast. The revolution he caused can be most easily found in his reassertion of the principle (lost in the Middle Ages) that knowledge, if it is to have any value, must be intelligence and not erudition. His application of modern arithmetic to ancient geometry created the analytical geometry which is the basis of the post–Euclidean development of that science. His statement of the elementary laws of matter and movement in the physical universe, the theory of vortices, and many other speculations threw light on every branch of science from optics to biology “. (Printing and the Mind of Man 129).