Secrets of the calendar

Secrets of the calendar
Accession number: 
MS. Opp. 701, folios 4v-5r
Bodleian Libraries, University of Oxford

This Hebrew manuscript contains rules for the calculation of the Jewish calendar. On the right, a man climbs a ladder into the sky to observe the movements of the heavens and learn the secrets of the calendar. The celestial world is represented by colourful clouds that surround a crescent Moon, emphasising the importance of lunar observation in time-keeping.

(probably Ashkenaz, 1586)

César Merchán-Hamann, the Bodleian's Curator of Hebraica and Judaica, describes the manuscript in more detail: 

MS. Opp. 701 (Neubauer 2056) contains a Sefer Evronot (Plural: Sifre Evronot), or Book of Intercalation. The manuscript, which contains other astronomical works, was produced in the German lands (Ashkenaz) in 1586. It is one of a number of books aimed at facilitating the calculations necessary for the adjustment of the Jewish calendar. The Jewish calendar is lunar, rather than solar like the Western calendar now universally in use, and hence needed adjustment if the festivals were to be celebrated during the appropriate season. A careful calculation of the moon-cycles was necessary for this. Usually, the codices were profusely illustrated in an unaffected style.