timelets

“They said that the Egyptians were the first of all peoples to discover the year, by dividing up the seasons into twelve parts to total one year, and that they discovered how to do this from the stars. The Egyptians seem to me to be much wiser than the Hellenes in the way they regulate the timing of the seasons. While the Hellenes attempt to preserve the timing of the seasons by inserting an intercalary month every other year, the Egyptians divide the year into twelve months of thirty days each and add just five days each year beyond that number, and thus their seasons do return at the same periods in the cycle from year to year.”

--- Herodotus, Histories.

The calendar is an amazing invention because it lets people keep time without checking the stars; the ultimate simulator.