Ancient Inventions

Days of the Week

The modern Western world owes it calendar to the Romans, who, after struggling for some time with an eight-day week, eventually opted for the Babylonian system widely used in the Near East from the third centry B.C. onward. The Romans simply exchanged the names of the Babylonian planetary gods for their Roman equivalents. Thus the day of Nabu, the Babylonian god of scribes, became the day of Mercury, the Roman god of communication. The Latin names of the days are still followed closely by the French and Italians, for example the Roman day of Mercury simply became Mercoledi in Italian.

In the English language the translation went one stage further, when the pagan Anglo-Saxon ancestors of the English borrowed the day system from the Romans and adapeted to their own gods. In this northern European system (also used by the Vikings), Jove or Jupiter (the thunder god) was known as Thor. Hence Babylonian Marduk's day became the Roman day of Jove, French Jeudi and our Thursday (Thor's day), and so forth.

While the choice of seven days reflects the number of planetary gods, the sequence does not reflect their traditional order, based on the ancient understanding of the solar system's arrangement: Saturn, Jupiter, Mars, Sun, Venus, Mercury, Moon. It instead comes from another great invention of ancient astrology, which we still follow—the division of the day into twenty-four equal units of time, or hours. The planet gods, in their traditional order, took turns presiding over the hours. For example, Saturn controlled the first hour of Saturday, to be followed by the other six gods until the seventh hour. The cycle began again with Saturn on the eighth, fifteenth and twenty-second hours. The twenty-third and twenty-fourth would be dedicated to Jupiter and Mars, and the first hour of the day would fall to the Sun god, the next in sequence. The Sun god therefore presided over the day.

A simple device for calculating the day names from the planetary hour gods was invented. By arranging the gods on the points of a seven-sided figure one can read off the order of the day gods by following the diagonals. When, and by whom, this handy geometrical trick was first invented is unknown, but an example of such a figure is provided by a graffito found at the Roman city of Pompeii.

Thus the names, number and order of our days of the week are dictated by the logic of ancient astrology. Another interesting fact: when the Babylonians invented the seven-day week, they anticipated the findings of 20th century biologists. It has recently been discovered that the human body is governed by a seven-day biorhythm, which is detectable from small variations in blood pressue and heartbeat as well as response to infection and even organ transplants. The same biorhythm affects other life-forms, even simple organisms such as bacteria.

Simple device for calculating the order of the days of the week

Read about other ancient inventions that shaped history and paved the way for modern inventions.