What remains unchanged over time?
Things that are convenient are not changed or investigated! That's how they remain constant, timelessly...
Well, timelessly yes, but just think, how timeless does something sound that has been convenient and therefore has remained unchanged for 5000 years? We have a system of subdividing time, which if you think about it, if you go to investigate it, you might find it a bit odd... We divide the day into 24 hours, the hour into 60 minutes, the minute into 60 seconds. "Why so?" One might say. And what's more, who told us to do it that way? Since when do we have this system?
So there was once a civilisation, the Sumerians, whose empire did not last long. The map shows their territory. They lived in Mesopotamia before the Babylonians. The Sumerians, first of all the Mesopotamian peoples, had a useful - as it turned out - habit of looking intently at the sky. They also had another useful habit; in their measurements they used the hexadecimal system (multiples of 6) and not the decimal system (multiples of 10).
The number 60 was, for the Sumerian astronomers, a magical number, as both the movements they observed in the sky and their everyday life were expressed by this number. On the one hand, the divisors of 60 are 1, 2, 3, 4, 5, 6, 10, 12, 15, 20 and 30 and serve the times of the observed celestial movements; on the other hand, the Sumerian calendar year was an exact multiple, i.e. it had 360 days. As for the 24-hour day, this was due to the fact that sundials measured hours during the day but not at night. The system of measuring the hours of night - during which the sun does not exist, but stars do - was based on 36 star groups called 'decans'. These decans divided night-time into 12 hours which, combined with the 12 hours of day-time, gave the 24-hour day.
Since the above Sumerian calculations have proved to be quite accurate and convenient, for 5000 years, no one has any reason to make any changes! The Sumerian method has therefore proved to be constant over time!
