Computing time has been a human obsession for millennia, and the disputes about the precise length of the solar year were constant from ancient times through the Middle Ages and even more recent centuries. The Gregorian Calendar took many years to find general acceptance in Europe - in England, for instance, Eliabeth I ran into religious opposition against introducing any initiative from Rome.
Arab and Jewish astronomers play a leading role in this wide-ranging survey (which has become a best-seller) of how humanity has tried to set the clock right - an obsession which primitive people, in particular, often regard as futile and irrelevant to their way of life: the sun and the seasons are enough for them.