Say, it’s the 12th century and you want to blog something about the politics in your region. You have no excuse that blogging hadn’t been invented yet. You pick up a chronicle which someone else, perhaps a colleague or a brother, had started some 50 years ago and you draft your post. You make sure you date-stamp it: the fifth kalends of November (28 October). You may even time-stamp it if you kept time in line with the local church bells (the sky is overcast and you can’t tell the exact time by the position of the sun). Just after terce (8:30 a.m.) will do. Everybody knows what year it is, but you write it down nevertheless, the year of our Lord dot dot dot, according to the Dionysian reckoning. This is to explain to those reading your post that you’ve given the year since the birth of Christ, as proposed by the 6th-century Scythian monk Dionysius Exiguus. Dionysius developed the idea of the Anno Domini, the reckoning of years from Jesus’ birth, rather than his death and resurrection. It’s the system we use today, even when we decide not to acknowledge its origin by replacing A.D. (anno domini, the year of the Lord) with C.E, common era. The secularisation of acronyms, who would have thought?
Your rant being over, you consider whether you’ll write another one before the year is out. Probably not, as things are already bad in your area and everything that can go wrong has been covered in past annals by yourself or someone else. The possibility of an ignoble leader staying in power doesn’t incense you as it used to. So you put the quill down and go to Mass.