A number that comes from the mud
On clay tablets baked four thousand years ago, Babylonian scribes pressed wedge-shaped marks to note their calculations. These people didn’t count like us. Where we group by ten, they grouped by sixty. A base-60 system, called sexagesimal.
Why sixty? One theory rests in the hand. With the thumb, you can count the three segments of each of the other four fingers: twelve slots. The other hand raises a finger each time you reach twelve. Five fingers, five bundles of twelve, and there’s sixty. The body served as an abacus.
The number that shares the best
Sixty has a quality ten does not: it cuts cleanly. You can divide it by 2, 3, 4, 5, 6, 10, 12, 15, 20, 30. No decimal point, no remainder. For astronomers carving up the sky and merchants splitting sacks of grain, it’s a godsend.
The Babylonians watched the sky with obsession. They had noticed that the Sun seems to circle the sky in a little over 360 days, advancing one notch each day along its loop. Many historians see there one of the reasons for choosing 360 to divide the circle. The link is still debated, and is surely not the only cause.
The count came out even with their base 60: 360 is six times sixty. A circle divided into 360 pieces was therefore a circle you could cut every which way without ever landing on an awkward figure.
Four thousand years unchanged
The real mystery isn’t that Babylon invented the degree. It’s that we still use it. The Greeks inherited this division, notably the astronomer Hipparchus and then Ptolemy, who built their sky tables on the Babylonian 360 degrees. From Greece, the figure passed to the Arab world, then to medieval Europe, without anyone thinking to change it.
The decimal system arrived much later and conquered everything, except that one corner. We measure lengths in metres, weights in grams, but angles stay in degrees, and time in hours of sixty minutes, each of sixty seconds. The minute and the second are the last direct heirs of base 60, hidden in our watches.
Reformers did try to modernise all this. During the French Revolution, they proposed the gradian, which splits the circle into 400 parts, the right angle then worth a round 100 gradians. It was logical, decimal, clean. Almost no one adopted it.
The degree survived out of pure habit, like an old word we keep saying without knowing where it comes from. Every time a compass reads 90 degrees or a circle closes on 360, a scribe of Babylon presses one more wedge into the clay.
