Gregorian Calendar.- Kalendarium Gregorianum perpetuum [graece], collation: A-M^4, [48]ff., Greek type, printed in red and black, title with woodcut coat-of-arms of Pope Gregory XIII, decorated and animated woodcut initials, numerous diagrams and tables, spotted throughout, some leaves uniformly browned, slightly soiled in places, recto of front flyleaf with pencil bibliographic notes and inked date 'Nov. 1757', late 18th-century vellum, corners slightly bumped, 4to, 242 x 162mm., Rome, Francesco Zanetti, 1583.

⁂ Sir Thomas Phillipps' copy of the rare first edition in Greek of the Gregorian calendar, which is still in use today. The reformed calendar replaced the Julian calendar, instituted by Julius Caesar in 46 B.C. and then amended at the Council of Nicaea in 325. It was promulgated by Pope Gregory XIII (after whom it was named) in a bull issued on 24 February 1582 in order to correct the miscalculation of the length of a year in the Julian calendar, and to make up for all the days that had accumulated. In the same year Latin editions of the Kalendarium Gregorianum perpetuum appeared in Rome and Venice; Italian, Greek and French versions followed in 1583. The Veronese Giovanni Battista Gabia was responsible for the translation into Greek. Curiously, the Greek Orthodox Church did not adopt the Gregorian calendar until 1923.

Provenance: Cardinal Mario Compagnoni Marefoschi (1714-1780; ex-libris on front pastedown); the great collector Sir Thomas Phillipps (1792-1872, shelfmark on front pastedown).

Literature: Ascarelli 151; Houzeau & Lancaster 14198bis; Riccardi I 636.