Calendar

This calendar shows three dating systems: the Christian calendar, the Jewish calendar and the French Revolutionary Calendar. In the Jewish calendar, the months were determined according to the Moon and the year according to the Sun. The order of the days of the month therefore varied a great deal. As a result, complex calculations were required to coordinate the Jewish and Christian calendars. Jewish traders in particular depended on calendars to avoid clashes with Christian holidays on long trading trips to markets and fairs.