KEPLER, Johannes

Francofurti [Frankfurt]: Apud Claudium Marnium & Haeredes Joannis Aubrii, 1604

4to, pp. (xvi), 449, (18) index and errata, 1 engraved plate of the eye and 1 leaf of explanatory text, 2 folding letterpress tables, numerous woodcut figures in the text. Upper outer corner of title-page neatly restored, tiny hole in lower part of title, signatures K and P browned (as usual) and light foxing elsewhere. 19th century red quarter morocco, spine gilt in compartments, marbled sides, marbled edges and endpapers, good copy. Bookplate of David L. DiLaura.

FIRST EDITION of Kepler’s first book on optics and a highly significant work in the history of ophthalmology in which he defined the optics and function of the eye. Kepler clearly defined the concept of the light ray, which was the foundation of modern geometrical optics, as well as the formation of images from pin-holes and the nature of images from mirrors and lenses. The work is in two parts: the first part, which Kepler intended to be an appendix to Witelo (hence “Ad Vitellionem paralipomena”) is “a treatise on vision and the human eye in which is shown for the first time how the retina is essential to sight, the part the lens plays in refraction, and that the convergence of luminous rays before reaching the retina is the cause of myopia” (Garrison p. 260). Kepler describes the nature of central and peripheral vision and demonstrates the part that the vitreous plays in keeping the retina taut. The second part, the “Astronomiae Pars Optica”, comprises six chapters which “include not only a discussion of parallax, astronomical refraction, and his eclipse instruments but also the annual variation in the apparent size of the sun. Since the changing size of the solar image is inversely proportional to the sun’s distance, this key problem was closely related to his planetary theory; unfortunately his observational results were not decisive” (DSB). This book contains “the first correct physiological explanation of the defects of sight, with a theory of vision, the first suggestion of the undulatory theory of light, an approximately correct formula of refraction (pointing out the relation between the sine of incident and refracted rays), the first announcement of one of the principal axioms of photometry, his method of calculating eclipses, still in use, etc. etc.” (Sotheran 5300). DiLaura, Bibliotheca Opticoria, 52. Caspar, Bibliographia Kepleriana, 18. Cinti, Biblioteca Galileiana, 13. Parkinson, Breakthroughs, 1604. Becker catalogue 216.1. Albert, Norton & Hurtes 1226.

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