For an economy to function efficiently, a society needs to develop basic methods of timekeeping and noting the passage of time. For the Romans, each day was divided into two periods: the time when it was light outside, and the time when it was dark. Each of these periods was then subdivided into hours. Superficially, this sounds a lot like our modern system of 24 hours in a day. However, there was one rather significant difference: Roman hours were not of a fixed length because they were simply equal to the amount of light or darkness on a given day divided by twelve. Since the amount of daylight varies greatly from day to day over the course of the year—with perhaps as many as 15 hours of daylight in the summer and only 8 or 9 in the winter—a Roman hour in the summer might be equivalent to a modern hour and a half, and, similarly, in the winter, a Roman hour might be only 40 of our minutes long. When telling time, the Romans referred to the hour after sunrise as the "first hour of the day," the next as the "second hour of the day," and so on up to the 12th hour. The 12 nighttime hours worked in the same way except that the starting point was sunset. Thus, you would have the first or second hour after sunset and so on. The length of an hour changed from day to day, so meetings could only be set very approximately. If, for example, someone said, "Meet me at the fifth hour," you simply had to make your best guess when that might be.
To indicate a given year, the usual method was to refer to the names of the two consuls elected for that year. Thus, for example, to specify the year 59 Bc, the Romans would have said "in the consulship of Caesar and Bibu-lus" since those two men were the consuls for that year. In practice, this meant that one had to carry around a mental list of all the pairs of consuls in Roman history in order to tell dates—an impressive feat of memorization and obviously a somewhat awkward procedure. To get around this, the Romans sometimes used an alternate numbering system for the years. In this scheme, they dated things from the foundation of the city of Rome, which in our numbering system was 753 BC. Thus, a Roman might say, "such and such happened in the 480th year since the city was founded." The Latin phrase for "from the foundation of the city" is ab urbe condita. When the historian Livy wrote his account of the entire history of Rome, he titled this work Ab Urbe Condita, suggesting that he was going to tell everything that had happened since the city was founded.
Like us, the Romans divided the year into 12 months. During the republic, they only had 355 days in a year. Since, as we know, there are really 365 and one-quarter days in an astronomical year, after a few years, the calendar began to get severely out of line with the natural seasons. If left uncorrected for long enough, this could have had disastrous consequences for farmers, since it might have led to their planting crops at the wrong time of year. The solution that the Romans came up with was that every so often the priests declared an intercalary month. This was a month without a name inserted between two existing months in order to bring the months back into line with the natural seasons. Since there was no set time table for inserting intercalary months, in times of crisis when the priestly colleges were not meeting regularly, the calendar could get way out of line. The most obvious example of this occurred in the Late Republic during the civil wars between Julius Caesar and his rivals. By the time Caesar emerged as sole ruler of the Roman world, the calendar was off by a full six months, and Caesar had to insert six intercalary months all at once. Therefore, in the late 40s bc, there was one extra-long year that was, in reality, one-and-a-half years long.
To make sure that this did not happen again, Caesar undertook a major reform of the Roman calendar. He added 10 days to the calendar, making a year 365 days long. Like our own months, each of the Roman months had between 28 and 31 days. To take care of the extra quarter of a day, Caesar institufed the leap year, so that every four years there would be one extra day added. This reformed calendar, known as fhe Julian Calendar, is pretty much the same one that we are using today.
The modern names of the months are all derived from the Roman ones. The Roman names were Januarius, Februarius, Martius, Aprilis, Maius, Junius, Julius, Augustus, September, October, November, and December, The names of January through June refer to Roman gods; for example, January is named after the Roman god Janus. The months of July and August were named by the Romans to honor Julius Caesar and the emperor Augustus. (Originally, July was Quinctilus, "the fifth," and August was
Sextilus, "the sixth.") The names for September through December are derived from numbers, with September meaning "the seventh," up to December, "the tenth." The reason December was called the 10th month rather than the 12th one is that the Romans began each year on March 1 rather than on January 1.
To indicate a day within a month, the Romans did not say, as we would, "on the 17th." Instead, they picked three days of each month, which they gave special names, and then indicated all other days by their relationship to these three. The first day of each month was known as the kalends of the month. The day of the month on which the moon was full was called the ides, which usually fell on what we would call the 13th or the 15th of the month. Finally, the nones was the day nine days before the ides. Because the Romans used an inclusive numbering system, the nones fell on what we would call the 5th or the 7th. One of the more famous dates in Roman history, for example, was the Ides of March, the day on which Julius Caesar was assassinated. According to our calendar, this would be March 15. For all days that were not one of these three, the Romans would designate it by the number of days before the next of fhe special days. Thus, for example, if fhe Romans wanted to indicate March 13, they would say, "three days before fhe ides of March."
A lot is known about Roman calendars because the Romans were very fond of putting calendars on the sides of their public buildings or temples, either actually carved into the stone or else painted on it. The letters were painted in red on a white background. These calendars listed not just the dates, but also almost always commented about important days as well. Such a calendar is known as a fasti. AW fasti consisted of 12 vertical columns, one for each month. Each month column was further subdivided. First came the name of the day. Next was a column of the letters A through H, repeating. This was to keep track of when market day came. For the Romans, every 8th day was market day, called nundinae. This cycle of days was the equivalent of our week. Thus, whereas we have a 7-day week because of Christianity, the pre-Christian Romans had an 8-day week. In a third column was an abbreviation that gave further information about what type of day it was. There were many of these types of days, but four were particularly important. The first type was symbolized by the capital letter F. This stood for dies fasti, of which fhere were 42 each year. These were the only days on which it was valid to institute a legal action. Days labeled N stood for dies nefasti, of which there were 58 per year. On these days, it was forbidden to conduct any legal business. The third type was marked with a C for dies comitiales, of which there were 195 per year. These were the only days on which the Comi-tia, the voting assembly, could meet. Finally, there were days marked NP, meaning dies nefasti publici. These were public holidays when no business should be conducted, and everyone had the day off to celebrate. There was no set number of holidays.
The Romans believed that certain days were luckier than others. Odd-numbered days were thought to be luckier than even ones, and thus all holidays began on odd-numbered days. The days after the kalends, the ides, and the nones were called "black days" and were thought to be particularly unlucky. Superstitious people tried to do as little as possible on these days and certainly would never begin any new endeavor on such a "black day."