CLAVIUS, Christopher (1538-1612). In sphaeram Ioannis de Sacro Bosco commentarius. Venice: Bernard Basa, 1596.

Clavius's anti-Copernican commentary on Sacrobosco's famous astronomical primer. Clavius was a Jesuit astronomer who contributed to the development of the mathematics curriculum and was one of the architects of the Gregorian calendar reform. His detailed commentary on the famous Sphaera mundi sought to bring Sacrobosco's Ptolemaic text up-to-date with sixteenth-century astronomy, and it quickly became a standard textbook in its own right. Clavius issued at least seven revisions of his text—which was printed in over 16 editions between the first in 1570 and 1618. Over time, he became more sympathetic to some Copernican ideas (although not heliocentrism) while refining his refutations of others. This particular edition mentions Copernicus by name less than previous revisions. EDIT16, 12683. Exhibited: "The Heavens Revealed," Chapin Library, Williams College, 2003.

Quarto (217 x 153mm). Woodcut armillary sphere on title, and woodcut initials, diagrams, and a printer’s device at end (dampstaining, a few closed tears, some foxing and toning). Later half vellum over paper boards, titled in manuscript on the spine. Provenance: old deleted ownership inscription on title – Nicolai Levy (signature on title) – Owen Gingerich (bookplate).