Greg and Julius sitting in a tree, 297 years apart.

Hold up a minute. Don't move on quite yet. Read this. I'm not insisting it's true, but think about your own life. How well do you remember what happened, when it happened or where? What year did you purchase your car? In what theater did you first see your favorite movie? Now imagine there was an anouncement that we'd been keeping track of time incorrectly and your calendar would be updated with a new system. Not only that, we won't have names for the last 15 years. When did you buy that car? That theatre closed down, sometime in the past 15 years or so. When exactly? Who knows, we don't have a good signifier for that time period. Or, we do, but it's special and perhaps complicated. Time is an odd thing that carries us along. If we don't pay attention to it, we'll get lost. Ever been swimming at the beach? Some time in the tide and you're 300 yards from where you started without even realizing it. So, is it possible that in a couple years you won't be able to describe the discrepencies that are confounding your memory?

Now imagine if a large bureaucracy with a questionable track record had the opportunity to adjust a calendar at the time when few people could read or write. Just think about it.

Further Reading:
Did the Early Middle Ages Really Exist? [pdf]