by Anthony Aveni
March 5th, 2010
This is a thoroughgoing treatment of the measurement of time across a broad range of cultures. Calendars are fundamental to civilization; farmers require a calendar know the best time to plant their crops. Thus, every civilization in history has had some kind of calendar. Many of these calendars, however, were independently developed and so use surprisingly different approaches. The Western calendar is based on the Mesopotamian calendar that posited 360 days to a year. It takes only a few years for such a calendar to get out of synch with the seasons, but the Mesopotamians weren't about to give up their nice round figure of 360 days to the year, so they added five "un-days" at the end of the year. These days were treated as grand holidays, times of celebration. So the Mesopotamian calendar actually consisted of 360 days in the "year" plus five extra holidays that didn't really count -- that was the reasoning.
The Egyptians added the one-quarter day to the year, which as adopted by Julius Caesar, bringing the Roman calendar up to fairly good standards; the problems with that calendar were not apparent until Europeans began taking precise measurements of the sky some 1500 years later.
The Mesoamericans (Toltec, Maya, Aztec, etc) developed a very different calendraic system in which the motions of Venus played a major role. The unit of measurement here was the tzolkin, 260 days long. They also had a year, which they called the haab, which was 365 days long. However, they divided the year not into months but into smaller units of 20 days. There were 18 of these units in a year, plus a special 5-day long period that was considered to be especially unlucky. Why did they choose a 20-day unit? Because they counted days by fingers and toes. Thus, instead of talking about "next Wednesday", they'd refer to "left pinkie finger day".
I must confess, I found this a rather dull book. Granted, the material is intrinsically dull, but I think that the author made it even duller by divagating into extraneous material. Entirely too much space is devoted to explaining the particulars of Inca culture, for example. While this clearly demonstrates the extensive research that the author carried out, it is not pertinent to the subject matter of the book and should have been excised by the editor.