Robert Garland investigates the ancient origins of the calendar and time-keeping systems of the Western world.
Our present system of timekeeping provides us with a year of fixed and unalterable length which requires only the intercalation of a single (leap) day every four years. We seem to hold the passage of time so securely within the palms of our hands that we can almost hear its quiet heartbeat. Our present calendar has become so accurate that it will take 44,000 years before it falls out of step with the sun by so much as a single day.
We are also agreed about our precise place within chronological time. There is no country on Earth that fails to concede the practicality of an absolute dating system based on a commonly agreed era date. It is true that some resent using the birth of Christ as their chronological benchmark and who continue to maintain their own idiosyncratic systems. Right-wing traditionalist Japanese, for instance, sometimes seek to reintroduce the system of dating in accordance with the year of the emperor's reign. Orthodox Jews date events from the day that the world was created, i.e. October 6th, 3761 BC. Muslims calculate from the year after the Hegira or flight of Mohammed to Mecca in AD 622, which makes the current year Ab Hegira, or AH, 1419. Hindus calculate from the birth of Bramha. No society, however, can any longer ignore the countdown of the Western calendar towards the year AD 2000. As the whole human race moves inexorably towards its encounter with the third Christian millennium, it may be timely to consider for a few moments how we come to be heading there in the first place. Our dating system is the construct of a variety of religious needs, pagan as much as Christian, including the need to establish fixed points in the solar year for the celebration of annual festivals.
Pre-industrial societies base their estimate of the year's length on a variety of repetitive occurrences in the natural world. These occurrences include changes in vegetative growth, the phases of the moon, the solstices, and the movement of the stars. Thus the Greek poet Hesiod, who lived in the seventh century BC, advised farmers in Works and Days to begin the harvest when the constellation known as the Pleiades was rising and to begin ploughing when it was setting, but to sharpen their agricultural implements when snails began climbing up plants.
For religious purposes, the phases of the moon provide a particularly convenient unit of time. The Greek religious year consisted of twelve lunar months, each twenty-eight or twenty-nine days in length from earliest times. A lunar calendar is useful for arranging the dates of monthly festivals and, perhaps, the payment of debts. But as a basis for determining the length of the solar year, the lunar calendar is virtually useless. Every two or three years it becomes necessary to insert (intercalate) an extra month. For civic purposes, therefore, the Athenians introduced a second calendar which divided the year into ten months, each thirty-six or thirty-seven days in length. The Egyptians used a calendar of twelve months, each of thirty days; at the end of the year they added five extra days. The decision not to base their calendar solely on the lunar cycle was prompted by the necessity to be alert to the annual inundation cycle of the Nile, which was sufficiently predictable to give them a more direct way of observing the solar year than was available to most early civilisations. Though even this calendar fell one day behind solar time every four years, it was the system, adopted and modified by the Romans, upon which our own calendar was ultimately to be based.
The earliest Roman calendar, dating perhaps as far back as the eighth century BC, consisted of ten lunar months, corresponding to the months later named Martius to December. Januarius and Februarius were added by Numa Pompilius (c.700), the second king of Rome, according to tradition, as the winter was originally excluded from the calendar altogether, reflecting the fact that this was a period of inactivity. …