In Why was the millennium considered such a big deal Cecil said “…the millennium” is the calendrical period beginning on January 1, 2001 (or, in the unenlightened view, January 1, 2000)…".
“Hey Cecil, where’s 200 Main Street?”
“Last house at the end of the one hundred block of Main Street.”
The first millennium started on January 1, 1 A.D., even though it wasn’t called that at the time. The previous day was December 31, 1 B.C. So, 2,000 years later, the second millennium ended on December 31, 2000 A.D., and the third millennium started on January 1, 2001 A.D.
Just try counting the years, if it makes you happier – but remember that there was no year 0.
You do realize that the first “millennium” in your scheme only lasted 999 years? :smack:
The difference between saying “the 2000’s” and “the Third Millennium” doesn’t appear to register with many people. :eek:
That’s correct; because for the addresses to be analogous to our system of dates, the first block of addresses would be 1 Main Street to 100 Main Street; the second block would be 101 Main Street to 200 Main Street. The twenty-first block would start with 2001 Main Street.
What’s that – they don’t number houses that way? Well, they number years that way, so I guess it’s not a good analogy.
That’s probably good advice. Just for being a smartass, Cecil would run you through the ancient Bleecker Street vaudeville routine (you can’t miss it) or, with a faux Vermont yankee accent, would say, “You can’t get there from here, bub.” 
I think a more pertinent conclusion would be “Don’t ask Will Repair what century it is.”
Will, try this one. You have a big pile of pennies and you want to count them and sort them into smaller piles of $1.
Should the 100th penny be the last coin in the first pile, or the first coin in the second pile?
…and of course, by extension, what will be the number of the first penny in the 21st pile? (Assuming you haven’t got tired of counting out those damn pennies.)
Of course we are also in the 20th century right now. You know, because it starts with a 20.
Thinking about how to explain why the 21st Century begins in 2001 I came up with a clever analogy way back in the 80s (Hey, I plan ahead). I patiently waited for someone to ask me about it but no one did. 
So now I get to inflict it on you.
Imagine you’re a prolific writer of short stories. Imagine also, that while you’re excellent enough that people love your stories as they are published in some magazine, you’re not very clever at thinking up titles for your stories. So, you number them instead, “Story 1” “Story 2” and so on.
Now imagine a publisher is interested in collecting your stories and publishing them in a book. Your stories are short enough that a hundred of them will make a nice-sized book, and in keeping with your naming scheme, the publisher entitles the book 1st Volume of So-n-so’s Stories. That book will have Stories 1 through 100 in it.
You keep writing and in due time 2nd Volume etc. is published with Stories 101 through 200 in it. Years pass and in due time 10th Volume is published with Stories 901 through 1000 in it. By now, the first volumes are out of print and the beloved ones extant are dog-eared and worn so the publisher reprints them in a big slipcase and dubs it 1st Collection with the 1st through the 10th Volumes, containing Stories 1 through 1000.
Year pass, more Stories and more Volumes are published until the publisher is ready to publish 2nd Collection with the 11th through the 20th Volumes, Stories 1001 through 2000. Everything is fine until someone objects, “Shouldn’t the 21st Volume and 3rd Collection start with Story 2000, not 2001?” I suppose it could, but then either 2nd Collection would have only 999 stories in it (stories 1001 through 1999) and everyone would feel cheated, or 2nd Collection would have Story 2000, and also 3rd Collection (with Stories 2000 through 2999). Chaos would reign – cats sleeping with dogs, the seven plagues. Better to leave everything as it is.
Substitute year for Story, century for Volume, and millenium for Collection.
And it shouldn’t.
Who actually thinks there’s a difference between “the 1900s” and “the 20th century”? Maybe a few anal-retentive nuts who don’t understand the purpose of these phrases. As counter examples you bring up counting money, an activity whose purpose is quite different, or short stories, whose ordinality no one’s gonna care about.
So you are saying that the first century AD only had 99 years in it (and the first millenium only had 999 years)? If you are not prepared to accept that the 1900’s are different from the 20th century then you must accept that a century doesn’t necessarily contain 100 years, or your definition is contradictory.
Yes, the reasonable thing is to get a little fuzzy. A “century” is always a hundred years, but the “first century” ended in the year 99. The “first century” wasn’t a ‘really’ a “century.” Go cry about it. It just doesn’t matter. Point is, it’s the far preferable alternative to saying “the 20th century isn’t the 1900s”.
Don’t you get the irony in this?
You’re happy to go along with the fact that the 20th century was the 1900s, but won’t accept that the 20th century started in 1901?
By your own logic, surely years 0-99 should be some kind of “zeroth century”, then 100 was the start of the first century.
Stupid? No more stupid than starting the second $1 pile of pennies with the 100th coin and leaving the first pile 1c short. Try telling the bank teller that you “started with coin zero” and see where you get… 
If you have consecutively numbered banknotes, and the first one’s number ends with 00, then the first hundred ends with the note numbered …99. That, of course, would be fine for years if there were a year zero. However, many years later, it was decided that AUC 754 was 1 AD, and AUC 753 was 1 BC. So you are, in effect, working with banknotes starting with the number 1, and the first century AD went from AUC 754 to AUC 853, i.e., 1 AD to 100 AD. (Though the AD numbering did not come into existence until some centuries later).
Hmm, it came out better in my first post. When counting money it’s the groupings of 100 that matter. When counting years, it’s the alignment that matters. Do people care that the 20th century was shorter than the 21st by one day? No.
It’s the other way round. The 20th century was 36,525 days long; the 21st century will be 36,524 days long. And since I won’t be around at the end of February 2100, no, I don’t really care.
I’m not happy with this situation either, but unfortunately that can’t be changed. “Zeroth” sounds dumb and will piss off the people who discuss the early Christians. In fact, the whole business about “nth” century came about because although it’s easy to talk about the “1700s” there’s no such phrase for the early years AD. Similarly, while noone talk about the “crazy hair of the 9th decade,” we’re gonna have no choice but to switch naming conventions and call our present, eventful period “the first decade of the 21st century.” Obviously it’ll still be the years 2000-2009.
did I win?
Is this a competitive sport?
But I still disagree with you. There ought to be a neat name for the decade 2000-2009, in the way that 1990-1999 is the 1990s and 2010-2019 will be the 2010s. However, it’s not the first decade of the 21st century, since that is 2001-2010.
As Giles pointed out, nobody in 99AD was counting that way. If we can renumber the years retrospectively in such an abstract and sweeping way, then we can choose to have a 99-year century. Popular opinion has already taken that decision, no matter how many clever analogies one creates.
There ought to be a neat name for the decade 2000-2009, in the way that 1990-1999 is the 1990s and 2010-2019 will be the 2010s.
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And 1900-1909? 1800-1809? These either get called ‘the 1900/1800s’ or described more exactly, depending on which the context requires for clarity. Such will almost certainly remain the case for the current decade.