To Pope Gregory XIII we owe the first chronological disorientation of the modern era, and Gregory's reform caused quite a bit of it. Here are the facts. In the 16th century A.D., which began with the year 1501, things are not going so well in Europe with the count of time. The fact is that Holy Easter, year after year, presents itself in an increasingly hot season. After consulting the astronomers, the pope realises that the reason for the postponement lies in the slight "dyscrasia" between the tropical and Julian years. The tropical year is nothing more than the time it takes the Earth to make a complete turn around the Sun. It lasts, exactly: 365.
The Julian year, wanted by Caesar in his calendar reform, launched in 45 B.C. on the model known in Egypt, lasts instead, for pure mathematical convenience, 11 minutes and 14 seconds longer: and amounts to 365.25 days. The arithmetic convenience lies in the fact that three years of 365 days can be alternated with a year of 366, to maintain the synchrony between legal and astronomical time. Between the tropical year and the year of Caesar, there remains, it is true, a gap of 11 minutes and change. But the error is small: equal to 0.002%. The trouble is that time sometimes amplifies even small errors. So, after 1500 years, dyscrasia amounts to a dozen days. To stop the sliding of legal time through the seasons, on the advice of astronomers, Pope Gregory orders that we stop considering leap years as leap years that end in double zero, unless, like 1800 and 2000, we are divisible by four. And, above all, Pope Gregory XIII orders that from Thursday 4 October of the year of grace 1582 we pass, in a single night, directly to Friday 15 October.
It is easy to imagine the chronological disorientation of the simple people who, from Rome to Madrid and Lisbon, are no longer caught between dates and deadlines. The time situation in Europe is also tangled up because Protestants, suspicious, fear that the greedy Pope of Rome, with his reform, wants to steal ten days of their lives from them. And they reject that papist devilry. What confusion! The continent is reduced to a sort of temporal puzzle. Henry III's France aligns with Rome's calendar, but only in December 1582. The Catholic states of Switzerland and Germany in 1584. Some resist until 1587. As for the Protestants, well they give in, yes, but much later. The last one is England, with its colonies: it will adopt the Gregorian calendar 170 years later, in 1752. In Russia, then, you see the oddities of the time, it was only the atheist revolution of 1917 (March or February?) that imposed the "papist" dating. Since the Julian calendar was still in force in Russia, as we have seen it was back to the Gregorian calendar, the February Revolution took place in March and the October Revolution took place on 7 November. It was the October Revolution that reformulated the Russian calendar, just as it reformulated Russian spelling to demonstrate the depth of its impact. And in China, it was Mao's revolution in 1949 that imposed the European calendar.
