Paralipomena to Witelo and the Optical Part of Astronomy

by Johannes Kepler

Translated by William H. Donahue

7" x 10", 475 pages, notes, two indexes, bibliography. Separateparallax tables in a pocket.
Publication Date: November 2000
For pricing and ordering information, see the ordering section below.

Optics cover The Optics, first published in Latin in 1604, was a product of Kepler's most creative period. It 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. First, 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 — though Descartes built on insights derived from Kepler's work. 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. Especially notable are Kepler's discovery of the inverted retinal image, his theoretical grounding of the inverse-square photometric law, and his insights into the relations between the various conic sections.

Among the treasures the Optics contains are Kepler's theory of the metaphysics of light and other quasi-material powers, a substantial commentary on Aristotle's theory of light, a remarkable, though ultimately unsuccessful, theory of refraction, and a fascinating speculation about the half-hidden heliocentrism of Euclid's Optics. The sections on parallax and atmospheric refraction are ancillary to the Astronomia Nova, 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.

The translation is accompanied by extensive footnotes (not endnotes). Nearly all the diagrams were drawn anew for this edition. The two exceptions are reproductions of Kepler's original illustrations, used where the sense of the text requires them. Kepler's original index has been retained, supplemented by a second index prepared by the translator.


  • Complete and unabridged translation: the only complete version in any modern language.
  • Extensively annotated, with footnotes rather than endnotes.
  • New diagrams and illustrations.
  • Two indexes: Kepler's original index and the translator's index.
  • Contains the first accurate account of the function of the eye.
  • Includes an innovative treatment of the mathematics of conic sections.
  • Presents the first precise geometrical explanation of the optics of pinholes.


In this book Donahue has performed service of enormous value to Kepler scholars and historians of early optics. His lucid translation of the difficult Latin of Kepler's great optical treatise not only affords ready access to Kepler's optical achievement (for the first time since Latin ceased to be the universal language of scholarship), but also reveals the clarity, rigor, and persuasive power of Kepler's arguments.

— David C. Lindberg
Hilldale Professor and Chair Department of History of Science,
University of Wisconsin

See Also

Selections from Kepler's Astronomia Nova by William H. Donahue

An annotated translation of selections from Kepler's greatest work. Much of the book is nontechnical in nature, discussing gravity, the earth's motion (in relation to both physics and scriptural interpretation), and the physical aspects of the planets' motions. An excellent, brief introduction to Kepler's thought.

A Science Classics Module for Humanities Studies
A Green Cat Book

Ordering Information for Johannes Kepler, Optics: Paralipomena to Witelo and the Optical Part of Astronomy

Sewn hardcover with dustjacket, ISBN 978-1-888009-12-5, list price: $55.00

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