The Calendar (6 page)

A generation after Aristarchus, the Alexandria-based mathematician, philosopher, geographer and astronomer Eratosthenes (276-194 BC) deduced within a tenth of a degree the tilting of the earth’s axis of rotation, which causes the seasons. He also measured the circumference of the earth to within 250 miles of the true value. A few years later Ctesibius of Alexandria constructed an elaborate water clock using floats, a chain winch, cog shaft, dial and a sundial system that linked the path of the sun astronomically and geometrically with levels of its shadow.

In about 130 BC the astronomer Hipparchus (fl. 146-127 BC) discovered the precession of the equinoxes, a slow shift westwards of the equinoctial points against the stars, something Isaac Newton much later determined was caused by the very subtle gravitational tug of the moon and sun on the earth. Hipparchus published a celestial catalogue, since lost, that described hundreds of stars and provided calculations about distances among them. He also confirmed the accuracy of the Egyptian year by studying several years’ worth of solstices to come up with a reasonably close approximation of the true solar year: 365 days, 5 hours and 5 5 minutes, some six minutes too long.

But none of these stargazers were as influential as Alexandria’s last great astronomer, Claudius Ptolemy. A Greek and a citizen of Rome who flourished some two centuries after Caesar’s sojourn in Egypt, Ptolemy compiled during the second century AD a massive encyclopaedia on astronomy and geography that became, with Euclid’s
Elements
on mathematics, a widely revered if not always understood textbook in the Middle Ages. Ptolemy’s calculations about the length of the month and year; the motions of the sun, moon and stars; eclipses; and the precession of the equinoxes became the benchmarks used by every time reckoner who followed him for over a thousand years: Bede, Roger Bacon and the chief architects of the calendar reform in 1582, Christopher Clavius and Aloysius Lilius. Ptolemy’s value for the length of the solar year, which he borrowed from Hipparchus, happened to be wrong by several minutes. Yet it is worth noting that Ptolemy and the Alexandrians knew Caesar’s year of 365 1/4 days was in error centuries before Roger Bacon--and some 1,400 years before Pope Gregory finally fixed it.

On the night of Cleopatra’s feast Caesar may have received an earful about Egypt’s calendar, but as it turned out he almost missed his chance to use it. That very night he narrowly avoided being killed in an attempted palace coup. Only the intervention of Caesar’s barber, a busybody who overheard the plotters, saved him. As it was, Caesar had barely enough time to protect himself and to muster his troops. After fierce fighting inside the palace, the general and his men managed to secure the royal compound, though this left them under siege by the boy-king’s army and a mob of anti-Roman Alexandrians. The Romans retained access to their small fleet, moored to the palace docks, but were blockaded from leaving the main harbour by Egyptian warships.

Foolishly, Caesar had come to Alexandria with only two depleted legions from the battle at Pharsalus. No more than 3,200 men and 34 ships were pitted against an Egyptian army numbering at least 22,000 men supported by a large Alexandrian navy. Fortifying the palace and securing the royal harbour, Caesar dispatched messengers to fetch reinforcements from his legions in Syria and Greece. He then launched a series of sorties to reinforce his position, at one point setting fire to part of the Alexandrian fleet. Tragically, these flames spread to the shore, destroying several buildings in the lavish Brushium district west of the palace, including buildings that housed part of the great library’s priceless collection. In another skirmish, fought over a causeway connecting the island of Pharos to the city, Caesar’s position was overrun, forcing him to swim for his life to a Roman skiff, pelted all the way by Egyptians who could easily single him out in his imperial purple toga.

Caesar ultimately prevailed, however, when a large relief force of legionnaires arrived some five months later. With these he crushed his enemy and restored his lover to her throne.

Caesar was now free to return to Rome, but delayed again, this time to celebrate his victory with a two-month journey with his mistress down the Nile. Luxuriating on an immense barge filled with banquet halls and apartments fitted out with cedar, cypress, ivory and gold, the general and the queen feasted, relaxed and made love, producing in due time a son that Caesar would later recognize as his own, calling him Caesarion. Hoping to float all the way to Ethiopia to discover the source of the Nile, Caesar during this trip undoubtedly continued his discourse with the sages of Egypt. These may have included a court astronomer named Sosigenes, who wrote several books about the stars, all of them now lost. But unlike those great stargazers whose works
have
been preserved, Sosigenes at some point during Caesar’s time in Egypt passed on something far more lasting than suppositions about the placement of stars and the distance of the sun and moon: a breathtakingly simple idea for reforming the Roman calendar.

In June of 47 BC, Julius Caesar finally departed Egypt. As a parting gift he left the pregnant Cleopatra three Roman legions to protect her, but also to guard the interests of Rome against a woman Caesar clearly understood was as ruthless as he in her ambitions. Desperately needed in Rome to sort out the aftermath of the civil war, Caesar first launched two lightning-quick wars against an upstart king in Syria and against the remnants of Pompey’s army, which had fled to the north coast of Africa. He then returned to Rome, where the Senate named him dictator for ten more years, commissioned a bronze statue of him to be erected in the Forum, and ordered a celebration of forty days for his victories in Gaul, Egypt, Syria and Africa. This triumph became a legendary orgy of festivals, games and debauches that included the slaughter of four hundred lions in the Circus, and mock battles on land and sea in which hundreds of war captives and criminals died. For days at a time Caesar’s soldiers marched in parades leading into the Forum, carrying more than 20,000 pounds of captured treasure and leading in countless prisoners weighed down by chains. These included the young princess Arsinoe, a sister of Cleopatra who had sided with her enemies.

Caesar’s supporters revelled in their triumph, though many Romans, raised in a republic that had for centuries despised the idea of a king, found the celebrations grossly ostentatious and an unsettling display of arrogance and personal power. The Roman historian Dio reports that people recoiled against the bloodshed and the ‘countless sums’ lavished on the shows. People also complained about the treatment of high-born prisoners, including Arsinoe. Demeaned in her chains, she ‘aroused very great pity’, to the point that Caesar released her rather than face the wrath of the populace. Not even a lavish gift of gold, grain and oil to every free person in Rome assuaged a general anxiety about what Caesar would do next. Already his enemies were talking darkly of a man whose success and virtually limitless power was turning him into a monster.

The fact that Caesar governed mostly with energy and resolve after his infamous fete made his enemies revile him even more, since an able dictator set back the cause of those who longed for a return of the republic far more than if Caesar had been inept. He plunged into a dizzying series of projects ranging from a flurry of new temples and a planned canal across the Isthmus of Corinth to hundreds of new laws and reforms. He dissolved the corrupt guilds in the city; limited the terms of office for senior elected officials; forgave a quarter of the debts owed by all Romans, to stimulate the economy; awarded prizes to large families to increase the population, depleted by the war; and reduced the expensive subsidies of grain to the city’s paupers. He also consolidated power by naming his own men to key offices and by co-opting control of the Senate.

But none of the measures taken by Caesar during his first months back in Rome was more dramatic than the one he decreed sometime in the first half of 46 BC; the reordering of the Roman calendar. More than a simple adjustment in the way days were counted, this reform was a potent symbol both of Julius Caesar’s newfound authority and of an empire that believed it had the power to reorder time--not only for its own people but for subjects living in far-flung locales, from the English Channel to what is now Iraq. Fortunately for the millions of people who would have to use his calendar, Caesar’s hubris coincided with the pragmatism of a veteran general and statesman who based his new calendar on science, not vanity or religious dogma. In any case, Rome’s old lunar calendar was in desperate need of reform, running in Caesar’s day several months fast against the solar year.

Like many other ancient cultures, the Romans centuries earlier had developed a system based on a 12-month lunar year, plus occasional days and months intercalated by priests to keep the calendar year more or less in line with the seasons. But over the centuries the calendar had drifted back and forth because the priests either neglected to insert extra months or because they intentionally manipulated the calendar for political reasons. For instance, the highly politicized college of priests sometimes increased the length of the year to keep consuls and senators they favoured in office longer, or decreased the year to shorten rivals’ terms. The college also misused their calendar to increase or decrease taxes and rents, sometimes for their personal financial advantage.

By legend, the Roman calendar--our calendar--was created by the mythic first king of Rome, Romulus, when he founded the city in 753 BC--year 1 in the Roman calendar, known as
ab urbe condita
(AUC), ‘from the founding of the city’. But unlike most moon-based calendars, Romulus for some unknown reason concocted a year composed of only 10 months, not 12, for a year that totalled 304 days. The ancient Roman poet Ovid (43 BC-AD 17), who wrote poems about love and about the calendar, submits that the erring warrior-king ‘was better versed in swords than stars’, and may have been trying to emulate ‘the time that suffices for a child to come forth from its mother’s womb’--a gestation period roughly corresponding to 304 days. Another reason may have been the Roman reverence for the number 10, says Ovid, ‘because that is the number of the fingers by which we are wont to count.’ Romulus repeatedly used the number 10 in organizing his new kingdom, dividing both the 100 senators and his military units of spearmen, infantry and javelin throwers into groups of 10. Latin numerals themselves--I, II, III, IV, V, VI, VII, VIII, IX, X--are probably symbols meant to represent fingers counting up to 10, with the V perhaps equating to an upraised thumb and index finger and the X to an upraised palm.

Romulus’s infatuation with ten extended to naming his months. In one of the more unimaginative bursts of calendar making, this ancient king started out attaching descriptive names to Roman months, then seems to have run out of ideas. The first four months he named Martis for the god of war; Aprilis, which probably refers to raising hogs; Maius, for a local Italian goddess; and Junius, for the queen of the Latin gods. Then he simply fell into counting the months, naming them the fifth, sixth, seventh, eighth, ninth and tenth: in Latin Quintilis, Sextilis, September, October, November and December. This mythic king’s lack of attention explains why the tenth, eleventh and twelfth months of our modern calendar are still numbered in Latin as the eighth, ninth and tenth months.

Romulus and his successors were equally unimaginative in their system of numbering days of the month. They divided up each month not into weeks, which were introduced in Europe much later, but into day markers that fell at the beginning of the month, on the fifth (or seventh) day and in the middle. These three signal days were called
kalends
(the origin of our word
calendar), nones
and
ides.
Most other days in the Roman calendar had no given name. Instead each was numbered in a confusing system according to how many days it fell
before
the kalends, nones or ides. For instance, here is the Roman system for the first half of March:

Modern Date   Roman Date

March 1            Kalends Martius 1st
March 2            VI nones (5 days before nones)
March 3            VI nones (4 days before nones)
March 4            IV nones (3 days before nones)
March 5            III nones (2 days before nones)
March 6            Pridie nones (day before nones)
March 7            Nones
March 8            VIII ides (7 days before ides)
March 9            VII ides (6 days before ides)
March 10          VI ides (5 days before ides)
March 11          V ides (4 days before ides)
March 12          IV ides (3 days before ides)
March 13          III ides (2 days before ides)
March 14          Pridie ides (day before ides)
March 15          Ides

Romans would refer to 11 March, say, as ‘Five ides,’ which was as clear to any other Roman as someone today saying ‘11 March.’ Still, given the complexity of this system, it is amazing that it lasted some two thousand years, operating as the official dating system in Europe well into the Renaissance. As late as the seventeenth century, William Shakespeare could write his famous lines in
Julius Caesar,
‘Beware the ides of March,’ and expect his audience to know what he meant.

Romulus’s 304-day calendar was shorter-lived, being entirely unworkable for an agricultural people who needed a reasonably accurate calendar to guide them through the seasons. It was Romulus’s successor, King Numa, who added two more months to the calendar around 700 BC--Januarius and Februarius. This brought the year to the standard lunar year of 354 days, to which Numa added another day because of a Roman superstition against even numbers.

This 355-day year was a considerable improvement over Romulus’s calendar, though it did not take long for Roman farmers to figure out that it too was flawed and needed days and months intercalated to keep it in line with the seasons. The Romans attempted several schemes to make the correction, none of which worked very well. First they tried adding an extra month every two years. But they miscalculated its length and overshot their mark, coming up with a 3667-day-long year on average. Realizing this calendar ran
slow
against the true year by a day and a quarter, the Romans adopted a version of the Greek calendar that inserted intercalary months every eight years. This brought their calendar roughly in line with a 365-day year, though the Greek system was so confusing that the priests frequently forgot to slip in the extra months at the proper interval or botched the job, causing calendric time to slip back and forth against the solar year.