The following is an e-mail concerning the 'is there a year 0' issue, sent to me by Sean Oberle in response to some comments about 'Y2K' made on my calendar page. It is published here by permission.

The article has also appeared in a few forums such as this one, but forums change rapidly; the above link is ephemeral.

Hello, Good to see another person who rejects this "no-year-zero" clatter. On your web site, you write: "...The system was established by the sixth-century scholar Dionysius Exiguus ('Dennis the Small'). About two centuries later, the English historian Bede began the practice of counting numbers before 1 AD as "BC" years. * Since the concept of zero and of negative numbers was unknown to him, he simply put 1 BC as the year before 1 AD, with no intervening year zero." You are on the right track Two historical facts support your argument: (1) Dionysius measured from incarnation, not birth. Though a theological oversimplification, think of incarnation as conception. Dionysius, significantly, set incarnation (and birth incidentally) in the yearbeforethe year he called 1 AD. (2) Dionysius set up his AD system to keep track of 19-year cycles related to the date of Easter year to year. The first year of his first cycle he also set in the year preceding the one he called 1 AD Both his benchmark (incarnation) and what he counted (19-year cycles) are set one year before 1 AD. It is clear that he thought of 1 AD as the second year of his count in the same way that we think of 1 a.m. as the second hour. And in the same vein, though the civilian clock "contains no zero" (starts with 12), the lack of 0 a.m. does not "prove" 1 a.m. is the first hour. (What, does the day start an hour earlier for scientists and soldiers because their clock contains a zero?) Similarly, the lack of 0 AD does not "prove that we must start counting with 1 AD." Dionysius thought of 1 AD as his second year, and so should we. Since 1 AD was his second year, by extension, 1999 is the 2000th. (Saying the millennium changes at 2001 is as factually wrong as saying Hitler invaded Poland in 1940.) In any event, for your enjoyment, I paste below an article I've written which explains it all in more detail. Enjoy: Midnight Is Not at 1 a.m., Now Is It? by Sean Oberle When it comes to the debate over 2000 vs. 2001 as the first year of the next millennium, there are three types of people (excluding those who just don't care). Those who correctly believe it is 2000, but have no idea why except that is what they've always thought. Those who think it is 2001 because they've fallen prey to that 'there's no year zero trap. And those of us who know it is 2000 because we've looked at the historical evidence and realized that the 'no year zero' clatter is just a red herring. In case you haven't heard this no-zero pitfall, here it is: 'There was no 0 AD, so the first year you count is 1 AD. Since a millennium is 1,000 years, the first two millennia were 1 to 1000 and 1001 to 2000. Therefore, the third millennium does not start until 2001.' All very simple. All very tidy. But then again, 'The earth looks flat; therefore, it must be flat' is very simple and very tidy...and very wrong. It's not that the logic of the no-zero folk is bad - it's perfectly good logic. It's that they apply their logic to a faulty premise. To get at their faulty premise, I'll start by asking: Why must 1 AD be the first year we count? Why must the count start with either a 1 or a 0? After all, when counting hours of the day, we start with 12. Isn't it possible that our calendar measures years the same way that the civilian clock measures hours, so that both 1 AD and 1 a.m. are tied to second not first, units? It's not just possible, it's the truth. You see, we measure time in two ways. The first I call Current Count, which we use to denote the time currently occurring. An example of Current Count is the first day of a month getting a 1. Current Count is what the no-zero folk wrongly assume the AD calendar does - that's their faulty premise. The second I call Time Passed, which we use to tally the time that has passed before the current point. An example of Time Passed is an hour of the day - 1 a.m. is tied to the second hour of the day. We also use it with peoples' ages - a child is called 1 during the second year of life. Note that it is the second unit, not the first, that gets tied to a 1. Note that I wrote 'tied to' not 'designated with'. And now that we know there are two ways to measure time, the assertion that 'there was no year zero' is a cop-out. First, there is rarely a zero in Time Passed - there is no 0 a.m. on the civilian clock. Second, the concept of zero was not much known in Europe when the AD calendar originated. Zero came from the East centuries later, so the lack of 0 AD may mean only that zero was not available. But the lack of 0 AD does not prove that 1 AD is the first year any more than the lack of 0 a.m. on the civilian clock proves that 1 a.m. is the first hour of the day. Now, Time Passed and Current Count are equally valid; they are just arbitrary conveniences that fit particular circumstances. But our calendar has been only one or the other since it began. That means that it doesn't matter how I think the years should be tallied. It doesn't matter what the no-zero folk think...or the good people at the U.S. Naval Observatory...or the kid who bags my groceries. What matters is what the fellow who set up the AD calendar was trying to do. If he set up Current Count, then the no-zero folk are right that the millennium starts in 2001. However, if he set up Time Passed, then 1 AD was the second year of his count, making 1999 the 2,000th year - meaning I'm correct in asserting that the next millennium starts when 1999 ends. The fellow who set up our calendar was named Dionysius Exiguus. That translates from Latin to Dennis the Little, so I'll call him Dennis. He was a Scythian monk living in Rome in the 6th Century. He set up the AD calendar while figuring out a system to tell when Easter should occur year-to-year. Dennis adapted a 19-year cycle of Easter dates. He set up the AD system counting from the incarnation of Christ. He tied the cycles to his calendar, and came up with a matrix of Easter dates. We don't use that matrix, but we still use his AD calendar. Therefore, the first year that he counted with HIS calendar should be the first year that we count. Let's try to figure out what year he counted first. A key to clearing up a lot of misunderstanding on this subject is in correcting one crucial but common error. Dennis was NOT measuring time from Christ's birth. He was measuring from Christ's incarnation. People read incarnation and assume it means birth. It does not. The incarnation occurred 9 months before Christ's birth. While technically wrong theologically, think of incarnation as Christ's conception. (Actually, miraculous incarnation takes the place of sexual conception in Christian theology.) The next step is being aware of one of the existing calendars that Dennis worked with. It was the Roman calendar that measured from the supposed founding of Rome. Its years are identified by AUC, which stands for the Latin phrase ab urbe condita, which loosely means 'from the city's founding'. The consensus of sources I've read is that Dennis calculated the birth of Christ to have been in 753 AUC, so he deduced that the incarnation must have occurred 9 months prior to December in March 753 AUC. Significantly, those sources also say that Dennis designated the following year to be 1 AD. Therefore, by Dennis' reckoning, Christ was incarnate during the year preceding 1 AD. Dennis must have been counting 753 AUC as the first year of his system just as we count 12 a.m. as the first hour of the day. After all, since he said he was counting years starting with incarnation, why would he have excluded the year in which he thought incarnation started? Reasonably, he would have included all years during which he thought incarnation occurred, making 1 AD his second year. Need further evidence that 1 AD was the second year? While we don't use Dennis' Easter-dating system, it also demonstrates which year he deemed the first. Remember, he tied the Easter system to his AD calendar. The Easter system consisted of 19-year cycles. Every author I've read agrees he designated 532 AD as the first year in a new cycle. But 19 is a factor of 532 (19 * 28 = 532), meaning that if 1 AD were his first year, then 532 AD would have been last, not first, in a cycle. The previous year, 531 AD, was the last year in a cycle, meaning that his calendar counted 531 'AD years' plus another. Where's that missing year? Logically, it must be 753 AUC, or in modern terms, 1 BC. Therefore, 1 AD is the second year of Dennis calendar, and, by extension, 1999 is the 2,000th. That means that when 1999 ends, that 2,000 years will have passed. The third millennium begins on January 1, 2000. But wait, you say. The year before 1 AD was 1 BC, and BC means 'Before Christ.' Isn't that significant? No. The BC system was developed hundreds of years after Dennis set up his calendar. The BC system has nothing to do with when Dennis thought the incarnation began. But wait, you say. Dennis calculated the birth of Jesus wrong, and the 'real third millennium' already has started. True enough, but that's a different issue. Dennis' calendar is what it is even if he based it on a faulty calculation. We are looking at when that calendar has ticked off 2,000 years. But wait, you say. Don't some people say Dennis set Jesus' birth in 1 AD? Yes, some do say that, but the combination of two facts suggests they are wrong. First, most authoritative sources I've seen say Dennis set both incarnation and birth in the year before 1 AD. But, I acknowledge, authoritative consensus does not assure correctness, so: Second, look back at the paragraph about the 19-year cycles. The year before 1 AD started his cycles, and he tied his cycles to the start of his calendar. But wait, you say. The U.S. Naval Observatory and other prestigious authorities take the no-zero side. So what? Prestige and authority don't make them correct. The USNO and others also say that Dennis was counting from Christ's birth and that he set Christ's birth in 1 AD. Both points are wrong. You probably are seeing that there are some pretty desperate no-zero defenses. That's because some no-zero folk don't want to give up. No-zero is so simple and tidy. It's pleasurable for no-zero folk to dazzle friends with the appearance of being in the know. Nonetheless, like flat-earthers, they are wrong. So, Mr. and Ms No-Zero, if you insist on clinging to your irrelevant no-zero argument, then be consistent. Don't celebrate the new millennium at 12 a.m. January 1, 2001. Wait an hour until 1 a.m. After all, there's no 0 a.m. on the clock, and by the no-zero logic, midnight MUST be at 1 a.m. Sure, everyone else will think you're silly, but you can take comfort in the illusion that you're correct. -- Sean Oberle Vice President of New Products Washington Business Information, Inc. 1117 N 19th St, Ste 200, Arlington, VA 22209 Voice: 703/247-3429; Fax: 703/247-3421