THE kingdom presented its shift from the Islamic to the Gregorian calendar as a leap into modernity. In April the dynamic deputy crown prince of Saudi Arabia, Muhammad bin Salman, chose to call his transformation plan Vision 2030, not Vision 1451 after the corresponding Islamic year as traditionalists might have preferred. Recently his cabinet declared that the administration is adopting a solar calendar in place of the old lunar one. Henceforth they will run the state according to a reckoning based on Jesus Christ’s birth, not on the Prophet Muhammad’s religious mission.

But puritans in Islam’s birthplace are wincing at their eviction from control first over public space, and now of time. Guardians of the Wahhabi rite, who seek to be guided by Muhammad’s every act, ask whether they are now being required to follow Jesus. A slippery slope, the clergy warn, to forgetting the fasting month of Ramadan altogether; the authorities are rewinding the clock to the jahiliyyah, or pre-Islamic age of ignorance. The judiciary, a clerical bastion, still defiantly insists on sentencing miscreants according to the old calendar.

The clerical unease has been matched by that of government employees. Under his transformation plan, the prince has already docked their perks and slashed pay. To add to their misery, they now complain they will have to work an extra 11 days each year. Yet another example, they gripe, of globalisation favouring rulers at the expense of the ruled.

A lunar calendar made sense when the moon was the simplest way of counting passing days. But for measuring years it is a poor approximation. It loses some 11 days a year, ensuring that Islamic holy days rotate round the seasons every 32 years. The Saudi administration, hopes one official, should now be more orderly and in step with the rest of the world. But having spent a lifetime learning dates from the year Muhammad fled from Mecca to establish the first Islamic state in Medina (622 in the Gregorian calendar), counting from Jesus’s birth is likely to leave many scratching their headscarves.

Still, Saudi Arabia is not alone in wrestling with ancient calendars. It is 1395 in Iran, 2628 in Kurdistan, and 5776 in Israel’s Knesset. Nor is it just the Middle East that is out of sync with the times. It is 2559 in Thailand, though only year 28 (of the Heisei era) in Japan.