Optics Author:Johannes Kepler The _Optics_ was a product of Kepler's most creative period. He had laid the foundations of his cosmology in the _Mysterium cosmographicum_ of 1596, and was in the midst of his great work on Mars's orbit, to appear as the _Astronomia nova_ (_New Astronomy_) in 1609. The same period saw the publication of the wonderfully speculative _De stella ... more »nova_ and other shorter works. The _Optics_ began as an attempt to give astronomical optics a solid foundation, but soon transcended this narrow goal to become a complete reconstruction of the theory of light, the physiology of vision, and the mathematics of refraction. The result is a work of extraordinary breadth whose significance transcends most categories into which it might be placed. It gives us precious insight into Kepler's thought during this crucial period, an insight all the more valuable in that most of his working papers from that time have been lost. Second, it is the culmination of a long and rich tradition in the science of optics, in distinct contrast with the new optical thought represented by Descartes. And third, it presents discoveries in the physiology of vision, photometry, and the geometry of conic sections which have become part of our intellectual heritage. Among the treasures it contains are Kepler's theory of the metaphysics of light and other quasi-material powers, a substantial commentary on Aristotle's theory of light, an original treatment of conic sections, containing Kepler's introduction of the term 'focus', mathematical theories of lenses and pinholes, an anatomical and physiological study of the eye, and the foundations of photometry. The sections on parallax and atmospheric refraction are ancillary to the _New Astronomy_, and are frequently referred to in that work. Unlike many other scientific works of the first rank, the _Optics_ is for the most part sufficiently nontechnical to be accessible to nonspecialists. At the same time, it is interesting enough to attract the attention of the educated layman as well as scholars in a wide variety of fields.« less