We’re more than ten years past our fears of Y2K and more than ten percent of the twenty-first century is now history.
As long as there have been human beings, they have kept track of the time. Through most of human history, that meant paying attention to the passage of the seasons so that crops could be put into the ground at the right time. Paying attention to months and days were secondary to that, and certainly paying attention to smaller fragments of a day came rather late in human history. The concept of punctuality as a virtue arrived only after the invention of the clock in the late 1200s. It wasn’t until the late 1400s that it became common for clocks to indicate minutes and even later for them to commonly keep track of seconds. The stimulus for accurate clocks was their value in navigation. The position of a ship at sea could be determined with reasonable accuracy if a navigator could refer to a clock that lost or gained less than about ten seconds per day. Such a level of accuracy was not achieved until 1761.
Only as timepieces became common—and really, only with the introduction of the industrial revolution, with factories and hourly wages and the like—did the concept of punctuality really take hold in western thought.
For most of human history, keeping track of the years was done by calculating them from the time the current king had taken the throne. So a date would be given as, “In the second year of King Darius, on the first day of the sixth month.” Such a date would have meaning only within the lands ruled by that king. The dates for a neighboring kingdom would be given in terms of that monarch’s reign. For historians, trying to figure out when something happened according to the calendar we use today is not easy, and the further back in time, the harder it becomes, with some dates, even of important, well-known events, having margin of error that can be measured in decades, if not in centuries.
Our current method of keeping track of time, with a twelve month calendar, seven day week, and counting from the approximate date of Jesus’ birth goes back to when Dionysius Exiguus came up with our current method of counting the year. At that time, the Diocletian Era was used for devising when Easter should be celebrated. But Diocletian had persecuted Christians, and so Dionysius Exiguus wanted to replace that calendar system for calculating when Easter should be celebrated.
The last year of the old system for determining when to celebrate Easter was Diocletian 247. The first year of Dionysius Exiguus’ new system started the next year, AD 532. AD is an abbreviation for the Latin phrase, Anno Domini, short for Anno Domini Nostri Jesu Christi, “In the year of Our Lord Jesus Christ.” Dionysius Exiguus’ new system of dating was only very slowly adopted. The Anglo Saxon historian known as the Venerable Bede used the AD system for his Ecclesiastical History of the English People which he finished in 731.
The AD system of dating was then endorsed by the Emperor Chalemagne (reigned 768-814) and his successors, which popularized the use of the dating system, at least within the Carolingian Empire (roughly corresponding to modern France and Germany). The popes in Rome continued to date documents according to their regnal years for quite some time, though the use of AD gradually become more common in Roman Catholic countries between the eleventh and fourteenth centuries. Portugal was the last Catholic nation to switch to the AD system of dating; they did so in 1422. Eastern Orthodox countries only began to adopt AD in place of the old Byzantine calendar in 1700, when Russia switched to the AD system of dating. The old Byzantine calendar had dated things from the supposed date of the creation of the world on September 1, 5509 BC.
By the nineteenth century, most nations on earth were using the AD system, though many continue to use alternate systems in addition to it. So, for instance, all Moslem nations date things according to the standard Moslem calendar which dates years from the Hijra, the emigration of Muhammed from Mecca to Medina. Thus, the current Islamic year is 1434 AH (After Hijra) which goes from the evening of November 14, 2012 to the evening of November 14, 2013. The Islamic calendar is a lunar calendar system, in contrast to the AD system which is a solar calendar. Likewise, the Hebrew calendar, used today in Israel alongside the standard AD system, is a lunar calendar and like the old Byzantine Calendar dates from the supposed date for the creation of the world—which is placed later than that of the Byzantine system. According to the Hebrew calendar, this is the year 5773, which began at sundown on the evening of September 16, 2012 and will last until sundown on September 4, 2013. Both the Moslem and Hebrew lunar calendars are brought back into sync with the solar calendar every four years or so by adding an extra month.