Final Report Summary - CALENDARS (Calendars in late Antiquity and the Middle Ages: standardization and fixation)
Calendars are familiar time-keeping devices that are convenient and useful, but also serve as fundamental structures of social and individual life. They determine how time is structured, measured, and conceived, and hence, how social activities and events are synchronised and structured. Calendars are culture-dependent, and determine, in turn, the norms of culture and society.
This project has examined how in the course of history, from Antiquity to the Middle Ages, calendars became increasingly standardized, unified, and fixed. This process was complex and closely related to politics, science, and religion. It contributed more widely to the formation of a unified and homogenous culture in the ancient and medieval worlds.
The standardization and fixation of ancient and medieval calendars was analyzed in this project through the perspective of five research areas: (1) the seven-day week, its origins, diffusion, and standardization in the Roman Empire; (2) the adaptation of Roman provincial calendars to the Julian calendar, as attested in the 'hemerologia' (comparative calendar tables) of late Antiquity; (3) the use of non-standard, fixed calendar cycles by medieval Jews; (4) the production and diffusion of authoritative monographs on the calendar by medieval Muslim, Christian, and Jewish scholars, especially al-Biruni in his Chronology of the Ancient Nations (1000 CE), and Isaac Israeli in his Yesod Olam (1310 CE); (5) the calendar controversy of 921-2 CE, which reputedly caused the Jewish calendar to reach its definitive, standard form.
Particularly noteworthy have been the following results and conclusions of our research:
1. The origins of the seven-day week. It has been established, through this project, that the seven-day week originated from two completely independent traditions: the Biblical week, originally specific to the Jews, and the planetary week, originally an Italian, popular astrological scheme. The week was ancient, but in both traditions its daily use, e.g. for marking dates, only began in the first century BCE. Over the course of the next few centuries, the two traditions merged, and the seven-day week became standardized and widely diffused. Christianity and the Christianization of the Roman Empire played an important part in establishing the week as a standard, universal time-reckoning scheme.
2. The standardization of the medieval Jewish calendar. It is commonly believed that the Jewish calendar was fixed in the 4th century, but this is historically incorrect. This project has studied how, in the early 10th century, the Jews of Iraq and Palestine disagreed about the calendar and observed the festivals on different dates. We have discovered, furthermore, that these differences persisted well after this event, at least until the 12th century. It is only then that the Jewish calendar became standardized and enshrined in a series of monographs on the Jewish calendar, starting from the early 12th century and culminating in the early 14th century with a monumental calendar monograph in Hebrew, 'Yesod Olam', composed in Spain in 1310 (an important but poorly known work, that we have studied in depth within this project). At the same time, an alternative Jewish calendar based on a cycle of 247 years was created in the late 10th century; as we have discovered, it enjoyed immense popularity across the Jewish world until the early modern period, in spite of its potential for the observance of the festivals on different, deviant dates, and challenging therefore the standard Jewish calendar.
3. Al-Biruni, The Chronology of the Nations. Al-Biruni was a Muslim scholar and polymath who wrote in Arabic, around the year 1000, an extraordinarily rich history of the calendars and chronological systems of all cultures in Antiquity and the early Middle Ages. Our study of this work, much of which has been preserved until now in only poorly accessible manuscripts, has opened a window not only on the history of calendars but also on the vibrant, multi-ethnic culture of central Asian Islamic society which al-Biruni most successfully portrays.
This project has examined how in the course of history, from Antiquity to the Middle Ages, calendars became increasingly standardized, unified, and fixed. This process was complex and closely related to politics, science, and religion. It contributed more widely to the formation of a unified and homogenous culture in the ancient and medieval worlds.
The standardization and fixation of ancient and medieval calendars was analyzed in this project through the perspective of five research areas: (1) the seven-day week, its origins, diffusion, and standardization in the Roman Empire; (2) the adaptation of Roman provincial calendars to the Julian calendar, as attested in the 'hemerologia' (comparative calendar tables) of late Antiquity; (3) the use of non-standard, fixed calendar cycles by medieval Jews; (4) the production and diffusion of authoritative monographs on the calendar by medieval Muslim, Christian, and Jewish scholars, especially al-Biruni in his Chronology of the Ancient Nations (1000 CE), and Isaac Israeli in his Yesod Olam (1310 CE); (5) the calendar controversy of 921-2 CE, which reputedly caused the Jewish calendar to reach its definitive, standard form.
Particularly noteworthy have been the following results and conclusions of our research:
1. The origins of the seven-day week. It has been established, through this project, that the seven-day week originated from two completely independent traditions: the Biblical week, originally specific to the Jews, and the planetary week, originally an Italian, popular astrological scheme. The week was ancient, but in both traditions its daily use, e.g. for marking dates, only began in the first century BCE. Over the course of the next few centuries, the two traditions merged, and the seven-day week became standardized and widely diffused. Christianity and the Christianization of the Roman Empire played an important part in establishing the week as a standard, universal time-reckoning scheme.
2. The standardization of the medieval Jewish calendar. It is commonly believed that the Jewish calendar was fixed in the 4th century, but this is historically incorrect. This project has studied how, in the early 10th century, the Jews of Iraq and Palestine disagreed about the calendar and observed the festivals on different dates. We have discovered, furthermore, that these differences persisted well after this event, at least until the 12th century. It is only then that the Jewish calendar became standardized and enshrined in a series of monographs on the Jewish calendar, starting from the early 12th century and culminating in the early 14th century with a monumental calendar monograph in Hebrew, 'Yesod Olam', composed in Spain in 1310 (an important but poorly known work, that we have studied in depth within this project). At the same time, an alternative Jewish calendar based on a cycle of 247 years was created in the late 10th century; as we have discovered, it enjoyed immense popularity across the Jewish world until the early modern period, in spite of its potential for the observance of the festivals on different, deviant dates, and challenging therefore the standard Jewish calendar.
3. Al-Biruni, The Chronology of the Nations. Al-Biruni was a Muslim scholar and polymath who wrote in Arabic, around the year 1000, an extraordinarily rich history of the calendars and chronological systems of all cultures in Antiquity and the early Middle Ages. Our study of this work, much of which has been preserved until now in only poorly accessible manuscripts, has opened a window not only on the history of calendars but also on the vibrant, multi-ethnic culture of central Asian Islamic society which al-Biruni most successfully portrays.