Our method of counting the years is due to a Scythian monk, Dionysius Exiguus, who in about 523 AD decided we should count the years since Jesus's birth instead of since the reign of the emperor Diocletian, who hadn't been particularly nice to Christians.
Unfortunately we do not know exactly how he determined the date of Jesus's birth, and of course, since he was working before the invention (some would say discovery) of the number zero, he started counting at 1 as well.
There are some methodological problems with determining the number of years involved. To start with, we don't know when Jesus was born. The Bible is quite specific that he was born during the reign of Herod (Matthew 2, 1; Luke 1, 5), during the reign of Augustus, when Quirinius was governor of Syria (Luke 2, 1-2). Unfortunately, according to the Roman author Josephus, Herod died in 4 BC, and Quirinius took up his office in 6 AD. But even if they were contemporary, Herod certain didn't die later than 4 BC.
So as you can see, we count the years from a date we don't know, forgetting to start at zero. If we want to add even more variability, while we are sure of the date that Jesus died, we haven't a clue about the month that he was born. Through history the year has started on different days, not always on January 1st (for instance some years began on March 25th 9 months before December 25th which almost undoes the error of forgetting to start at zero).
So considering all this doubt and uncertainty, it amazes me that anyone takes the time to worry about whether the start of the new millennium is now or in a year's time. As far as I am concerned, the important issue is that the most significant digit in the method of counting that we use is changing, and leave it at that.
Still, for those of you who somehow think that one of those mistakes in the calculation is more important than the others, and want to organise a party next year too, well... invite me!
In the meantime, from me, a happy new millennium to you all.
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