"A central database was necessary, among other reasons, because some of the me had to be properly timed. If people carried out the plowing-and-planting me at the wrong time of year, the harvest would fail and everyone would starve. The only way to make sure that the me were properly timed was to build astronomical observatories to watch the skies for the changes of season. So the Sumerians built towers ‘with their tops with the heavens'—topped with astronomical diagrams. The en would watch the skies and dispense the agricultural me at the proper times of year to keep the economy running."