KEPLER, Johannes (1571-1630). Harmonices mundi. Linz: Johannes Plancus for Gottfried Tampach, 1619.

First edition of Kepler's "mind's favorite child … a great cosmic vision, woven out of science, poetry, philosophy, theology, and mysticism," containing his third law of planetary motion (Caspar). Caspar's probable first issue, the title with allegorical device, and with the sometimes suppressed dedication to James I. This work, one of the most remarkable scientific treatises of the early modern period, "represents Kepler's attempt to discover God's archetypal model of the universe in the simple mathematical ratios embodied in the five regular polyhedrons, in the laws of musical harmony (based upon the seven ratios recently accepted as the basis of the 'just' scale), in his own theory of astrological aspects, and in the planetary system he had proposed in the Mysterium cosmographicum" (Norman). Book V refines the theories he had first explored in that earlier publication, using the knowledge gained over more than two decades experience to correct his ideas, hitting upon what is now known as Kepler's third law of planetary motion: that the square of a planet's periodic time is proportional to the cube of its mean distance from the sun. Although a major discovery, its full impact would not be felt for some time, when Isaac Newton took up the same ideas in his Principia. Norman 1207; Caspar 58. See also Max Caspar, Kepler, (1959, translated by C. Doris Hellman) and Aviva Rothman, The Pursuit of Harmony (2017).

Folio (283 x 187mm). Woodcut diagrams, illustrations, and printer’s device (lacking the 5 engraved plates, these supplied in sympathetic facsimile, a little soiling to title, deleted ownership inscriptions on errata leaf and title with a small hole). 19th-century quarter calf, spine gilt in compartments (spine and corners scuffed). Provenance: Owen Gingerich (bookplate).