Folio, (302 x 194 mm). 4 ff., 66 pp. plus 4 engraved plates, 255 pp. (63 foliated 73, 112 erroneously 198, 150 as 149, 200 as 100, 212 as 213, 228 as 225,229 as 226, 236 as 225, 237 as 231) plus one folding engraved plate; 50 pp. Contemporary vellum, spine lettered in ink, soiled and presenting old mold now stabilized, spine lettered in ink faded away and with paper labels in fragments at head and foot of spine, endpapers renewed. Some underlining, ink stamp ‘Biblioth[eque] Publ[ique] de L’Acad[emie] Roy[ale] des Scien[ces] de Bord[eaux]’ to title page, several contemporary and later manuscript inscriptions, colophon, first section title and a few scattered around in the text.

The Harmonices is one of the most remarkable scientific treatises of the early modern period, it is here, and previously in the Astronomia Nova (1609) that Kepler established the three laws of planetary movement, began earlier by Copernicus and Brahe.

“It was fortunate that Kepler was able to use the mass of material collected by Tycho Brahe. Brahe had greatly improved the construction of astronomical instruments and with these had made systematic and accurate observations over many years. Although he departed from the traditional picture of the universe on some critical issues, he regarded the idea of the motion of the earth as absurd: but he had lacked time to construct his own system of the universe from observation. This task he left to Kepler. Copernicus had shown the sun to be the centre of the universe round which the earth and planets revolve, but his description of their movements was still strongly influenced by ancient conceptions of order and harmony.

It was Kepler's aim to determine the true movements of the planets and the mathematical and physical laws controlling them. In this task he succeeded brilliantly. In the Astronomia Nova and in his Harmonices Mundi, published in 1619, Kepler explained his revolutionary discoveries, the three laws of planetary motion: (1) the planets move around the sun not in circles, but in ellipses, the sun being in one focus; (2) a planet moves not uniformly, but in such a way that a line drawn from it at any point in its orbit to the sun sweeps out equal areas of the ellipse in equal times; (3) the squares of the periods of the planets round the sun are proportional to the cubes of the distances.” (PMM).

In the Harmonices, the third law is published for the very first time, it was the basis for Newton’s gravitational theory in the Principia, that is when the full impact of the discovery was felt.

Kepler (1571-1630) “stands, with Galileo (u3), between Copernicus (70) and Newton (161) among the founders of modem astronomy and of a new conception of the Universe…” (PMM). “Kepler studied mathematics, astronomy and theology at Tiibingen. Compelled as a Protestant to give up his post as a teacher of mathematics at Graz, he joined Tycho Brahe, the famous Danish astronomer, at Prague and on his death became mathematician to the Emperor Rudolf II, a great patron of science.” (PMM, for the Astronomia Nova).

Provenance: title page with several contemporary ownership inscriptions, some scratched out at an early date, later 18th century stamp ‘Biblioth[eque] Publ[ique] de L’Acad[emie] Roy[ale] des Scien[ces] de Bord[eaux]’, a defunct institution around the French Revolution converted into a municipal library, which sold duplicates in 1787 (whilst we can’t firmly established this copy was at the sale, various later provenances would indicate so), also, the library organized another sale around 1805; ex dono from Prof. Barbot; loosely inserted early 19th century bookplate of an unidentified Benedictine Library, probably the Dioceses of Lausanne, Geneve; engraved signature of A. Graty (Adolphe Graty, 1805-1872) member of the French Academie (occupying the seat formerly held by Voltaire) and author, professor of moral theology at the Sorbonne.

Norman 1207; Caspar 58. See also Max Caspar, Kepler, (1959, translated by C. Doris Hellman) and Aviva Rothman, The Pursuit of Harmony (2017).