Calendars and Thinking Logically

By Fred C. Smith and Brant Abrahamson

The Teachers’ Press

Preface

The following is the student text for two short and enlightening lessons. The material may be freely photocopied for your students as the basis for a one- or two-period study session.

The first lesson (Centuries and Millennia) shows major religious and secular concerns that, in various ages, combined to produce the calendar with which we have recently begun “a new millennium.” The lesson is designed to combat “calendar occultism”—the irrational belief that mystical powers are associated with numbers.

The second lesson (Days, Weeks, Months and Years) focuses on the mathematical “messiness” of the earth’s journey around the sun (and the moon’s monthly trip around the earth). The complex interplay of physical phenomena, religion and science is an exciting interdisciplinary study.

The complete study material includes, in addition to this student narrative, a teacher’s text that is annotated (and heavily footnoted) in a spiral bound manual, with background, timeline, questions for extended discussion, multiple choice questions, and oral presentation material on Julius Caesar, Constantine, Dionysus Exiguus, and Pope Gregory XIII. 

You may order the complete booklet for this free mini-lesson (mailing costs only) from The Teachers’ Press using the order form. We hope it will encourage you to examine our more inclusive units, each of which is designed to be taught over a two- to four-week period.

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Part One: Centuries and Millennia

Introduction

'What year is it?" Most Americans--even quite young children--can almost immediately answer this question. They wouldn't ponder because our calendar is taken for granted. We "naturally" use it to determine schedules, calculate age, make loan payments and plan for the future. As we become educated we expand our historical horizons and understand that our calendar had a "starting point" about 2,000 years ago. We know that from this starting point most people count forward in "A.D." times and backward in "B.C." eras.

Further, we understand that other calendars exist. Most know of the age-old Chinese calendar. We're annually reminded of it during Chinese New Year celebrations.   We learn that they celebrate the "Year of the Rabbit" (1999) and other creatures in a twelve-year cycle that extends back more than 5,000 years. If we are followers of Islam or have studied the faith, we know the Muslim calendar begins with Muhammad's flight from Mecca to Medina in 622 A.D. (by "our" calendar).

Despite this intellectual understanding that a calendar is a human tool, many folks have superstitious beliefs linked to it. They see specific dates (days and years) as having magical powers in the same way they view four-leaf clovers or broken mirrors.

One frequent scary time is Friday the 13th of any month. Another that seems especially frightful right now has to do with the year 2,000 A.D. These fears go far beyond the so-called Y2K two digit computer problems currently being corrected.   So, what's the origin of the calendar that says the current year is number "1999"? Would people with occult-type beliefs about the "year 2000"--the "New Millennium"--be so concerned if they knew how this numbering of years came about? We'll see.

Origins of our Calendar

Generally speaking, people link their calendar to some important event in their history. The Chinese calendar is linked to what they believed to be the first Chinese Dynasty, and Muslims use an event in Muhammad's life. Much the same thing happened in Christian Europe.

Our way of numbering years was created around 1,470 years ago. Before this, the "Julian" calendar was used in the Roman Empire. Julius Caesar knew the existing system had flaws, and he wanted to develop a more accurate calendar. When he defeated Pompey's forces in Egypt (46 B.C.), he linked up with Cleopatra who was an intelligent and educated woman. She told him of her country's superior ways of measuring time, and had one of Egypt's expert astronomers meet with them. After returning to Rome, Julius Caesar started his reform based on what he had learned.

Caesar's new calendar had a cycle of three 365-day years followed by a fourth year of 366-days--the "leap year." The starting point of his calendar--the Julian calendar--retained the (legendary) founding of the city of Rome centuries before. It went into effect in 709 a.u.c. (ab urbe condita--from the city's founding).

Much later--after Christianity was made a state religion in the Roman Empire under Constantine (306-337 A.D.)--Christians began to want calendar years that referred to something of religious significance to them. The critical event for "our" calendar occurred about 200 years after Constantine--when Pope John I asked Dionysius Exiguus to determine when Easter celebrations would be held in the coming decades.   This was a difficult task since it involved the moon's phases coordinated to solar years. Dionysius, a Church abbot, was selected because he was trained in mathematics and astronomy. He started work on his calendar of Easters in (what would be) 525 A.D.

The calendar that emerged--our basic system for numbering years--included the Julian calendar's 12 months and Constantine's 7-day weeks.   It was the product of Church politics along with Dionysius's scholarship and guesswork.

The politics involved its starting point. Some Christians of Dionysius' time already were using a "Years of the Martyrs" calendar commemorating their last great Roman persecution under Emperor Diocletian. It was called the "anno Diocletiani" calendar, and its dating started when Diocletian became emperor in (what would be) 284 A.D.

Other Christians wanted the calendar based on Jesus' life. By Dionysius' time, most believed Jesus had been born divine, so basing the Church calendar on his birth made sense to them. It was the central historical point of their religion! However, fixing a date for the birth of Jesus was difficult. New Testament authors would have known of Roman and Jewish calendars, but these writers give no dates. Perhaps they thought dating was insignificant. Most believed that the existing times were about to end, and the "Millennium" was near--when Jesus would return and rule the world.   Probably they didn't know when Jesus had been born since the earliest Gospel birth accounts of the birth were written more than 80 years later.

At any rate, Dionysius calculated that Jesus was born 525 years before the time that Pope John I asked him to make the calendar of Easters. That placed Jesus' birth close to the beginning of the year 754 a.u.c.   Dionysius's first "year of the Lord" (Year One anno Domini--1 A.D.) corresponded to the Roman year 754 a.u.c.

Apparently there was a lapse in Biblical scholarship. The authors of the Matthew and Luke Gospels state that Herod was King of Judea at Jesus's birth, and Herod's death turned out to have been 750 a.u.c. According to these Gospels, therefore, Jesus had to have been born over four years before the 1 A.D. date!

In addition, the Matthew author says that King Herod was afraid of the baby Jesus and ordered male children two years and younger in the area to be killed. (Mary, Joseph and Jesus escaped by going to Egypt according to the account.) If accepted as history, Jesus may have been born nearly two years prior to Herod's death. This is why church historians say Jesus's birth was between 4 and 6 years "Before Christ." [1]

Christians gradually accepted the "A.D." calendar over the next few hundred years. It became the basis for dating religious celebrations and secular events.

When the errors in figuring Jesus's birth were realized, it seemed too late to correct them. Most people were unconcerned anyway. Their lives weren't affected very much.

The "Year One" Problem

Dionysius began his calendar with the year one. He couldn't begin it with "0"--such as we use--because there is no zero in Roman numerals. Roman "numerals" are actually letters: I, II, III, IV, V, VI, VII, VIII, IX, X, etc., along with L for fifty, C for a hundred, D for five hundred, M for a thousand.   The first century had to start with anno Domini I and end with C [100]. The second century thus began with the year 101 just as our 20th century began in 1901. As far as counting years is concerned, the 21st Century will begin in 2001.

"Arabic" numerals with the concept of zero were devised by Hindu/Indian scholars in South Asia sometime in the distant past. Arab Muslims brought them west and improved them, but they didn't become widespread in Europe until about the time of Christopher Columbus. What we write as 1000 A.D. was known then as the "M", or millennium year.

The Present Day

This brings us to our own "millennium times." Ancient Christian politics along with Dionysius' errors and calculation limitations are important to remember if religious significance is attached to the year 2000.

If we're measuring the time since Jesus was born--which Dionysius was trying to do--the third millennium already has begun! The "true" year 2000 A.D.--2000 years after the birth of Jesus has already passed! If other groups of Christians had won the political battles, we wouldn't be "facing the millennium" at this time. It would be very far into the future if we were still using the "anno Diocletiani" calendar.

As you see, our calendar has no cosmic origin or significance. What we will call the year 2,000 is the result of a variety of almost accidental happenings. It was developed in chaotic times by Christians using Roman numerals who believed Jesus was the Christ--the world's savior--when he was born.   But other notable times in early church history also were considered as starting points.

As a final note, this calendar is now used world-wide. Christian Europe's great political and economic power beginning about 1500 A.D. accounts for this fact.1   As one might expect, many non-Christians find the B.C. ("Before Christ") and A.D. (anno Domini --"In the Year of Our Lord") symbols objectionable. As a result, there's been a gradual change to "C.E." (common or current era) and "B.C.E." (before the common era). The numbering system, though, is exactly the same. "B.P." (before the present time) also is used for very ancient dating as is "Ma" which stands for "millions of years."

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Part Two: Days, Weeks, Months and Years

The "365 Day" Issue

Dionysius' "A.D." calendar continued to use Julius Caesar's system of having three periods of 365 days each followed by a fourth "Leap Year." This system worked okay for quite a while, but a solar year is about 11 minutes shorter than 365.25 days. The earth completes its orbit around the sun, but the Julian calendar is not quite over! As the years pass, the "left over" minutes become left over hours. After several hundred years the calendar was off by days! Real solstices and equinoxes came before their designated calendar dates. What to do?

Finally, in 1582--about a thousand years after Dionysius--a correction was devised. A committee of European experts who had been working on the problem convinced Pope Gregory XIII to use his power to correct things. They succeeded. In 1582 Gregory decreed a 10-day skip--from October 5 to October 15--so the calendar would have solstices and equinoxes in accord with astronomic observations.

The committee also "fine tuned" the Leap Year rule. The extra day (February 29) wouldn't be added in century "double zero" years--except when divisible by 400. For example, the year 1600 was divisible by 400 so it was a Leap Year, but not 1700, 1800 or 1900.   Year 2000 will have a February 29 as did 1600. This keeps the calendar accurate. It's now off by an average of only seconds per year, and there are rules for that.

Our calendar is sometimes called the "Gregorian calendar" since it was adjusted by experts at the time of Pope Gregory XIII. But like Dionysius's calendar, it took some time for the Gregorian revisions to be widely accepted even in many Christian lands.

The Protestant Reformation was taking place, and these leaders wouldn't accept decrees from the Roman Pope.   For instance, the English (Church of England) were battling Catholic Spain and France. English-controlled lands--America included--refused to officially accept the Gregorian calendar.[2]   When change finally came in 1752, their old calendar was 11 days behind. To catch up, all days between September 2nd and September 14th, 1752 were omitted. This was during George Washington's time, and he was born on February 11th, 1731 by the existing "old style" calendar. The Feb. 22nd birthday was calculated on the new calendar. Fortunately, corrections were made before the American Revolution. Otherwise, July 4, 1776, wouldn't be July 4th today!

Russia continued the old system until after the Communists took over. The Czars and most Russians belonged to the Orthodox Christian Church which historically looked to Constantinople for leadership, not Catholic Rome. The two branches of the church had grown apart and split in 1054 A.D. Russians--like western Protestants--rejected the "Pope's calendar" and continued to do so as long as the Czars ruled. Therefore, when Lenin and his Communist Party staged their 1917 "October Revolution", it was by the old calendar--as Washington's birthday had been. When they later adopted the Gregorian calendar, they had to celebrate their "October Revolution" in November!

Months

The cycle of years is determined by the earth's position relative to the sun.   A solar year is one earth-orbit around the sun. There are two solstices and two equinoxes.3   Even early peoples who believed the earth was stationary--with the sun, moon, planets, and stars revolving around it--observed solar years, and they divided them up in various ways. Our month and week divisions are one way of doing this. These are arbitrary, or human- made.

After Julius Caesar's calendar reform, Romans had a 12-month year with the odd circumstance that the ending "numbered months" were different from their numbers! September (from the Latin word for seven) had become the 9th month, October (8) had become the 10th month, November (9) was the 11th, and December (10) was the 12th. It happened this way: March originally had been the first month of a 10 month year. Then there was a switch to twelve months with January and February added; the year still beginning with March (although not March lst). The Julian calendar changed the order of the months. The new year now began with January. This left September, October, November and December as numbered months not corresponding to their numbers.   Apparently the Romans (including Dionysius) weren't bothered by this.

Are these ancient flip-flops important? Well, we do continue to abide by them. More important perhaps, they provide abundant evidence that calendars are human-made things based upon very human considerations, calculations and errors.  

A Week and its Days

The seven-day week system was ancient even when Julius Caesar ruled. Originally it may have been a crude division of the moon's cycle (of 29 days, 12 hours, 44 minutes, 2.8 seconds). Or, it may have come from ancient astrology. The names of days in Mediterranean cultures east through Mesopotamia all refer to the gods of the solar system bodies people could see.   In whatever language, these were deities associated with the sun, moon, Mars, Mercury, Jupiter, Venus and Saturn.

Emperor Constantine (324 to 337 A.D.) formalized Sunday as the first day of the 7-day week largely for political reasons. Sol--the sun--was still worshiped by many Romans. Constantine pleased these people as well as Christians. According to Biblical accounts, Jesus was crucified on the sixth day of the Jewish week and rose from the dead on the first day of the next week--a Sunday. As a consequence, for a long time Christians had gathered together on this day to share a meal, the Eucharist.

Our names for the days of the week are Anglo-Saxon words for solar-system gods. Is this another oddity? One might think Christian leaders would have been unhappy about continuing to honor old "pagan" deities. However, from earliest times they accommodated practices of other cultures to gain acceptance and make conversions.

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Part One: Questions and Projects

1. When did you celebrate the new millennium? Why then?

2. What year would it be now if "anno Diocletiani" calendar supporters had won? 3. When writing history essays, will you use "B.C./A.D" or "B.C.E./C.E."? Why?

4. What elements of our calendar's history surprise you the most?

5. Determine the number of the current year based upon another calendar.

6. Investigate the Chinese calendar, or one from another culture. How was it kept in sync with the solar year? How is the date for a major cultural or religious celebration--such as Passover (Judaism) or Ramadan (Islam)--determined?

7. What is "the millennium" in some Christians' belief? Does it specifically relate to the year 2000 A.D.? Why, or why not?

8. What drawing, diagram or picture would help children to understand this lesson? Make an illustration that you believe would aid them.

Part Two: Questions and Project

1. How many months are in the Jewish calendar? The Islamic calendar? How was the Julian calendar's "minutes then hours then days ahead" problem avoided by these calendars?

2. What are the names of the months and weeks in Spanish or some other language? Interview a friend or relative who speaks the language. Do they have the same origin as in English?

3. People also group calendar years. We use decades, centuries and millennia. Does it make sense to organize history by years ending with zeros? Is our historical understanding helped by talking about life "in the 60's"--as if 1960-69 were a distinct historical period? Is our understanding of historical situations and cultural periods distorted by using "round numbers" in this way? Or, are they necessary if we are to remember things at all? Do we attribute mystical significance to them?

4. Why was no one in England or her American colonies born between September 2nd and 14th, 1752? Were people in France and Spain born between these dates? Did George Washington really lose days out of his life?

5. Why was there resistance to the Gregorian calendar? Where did it last the longest?

6. Think of "Friday the 13th." Is the time fearful to anyone you know? Does it affect their behavior? How can such fears be overcome?

7. What drawing, diagram or picture would help children to understand this lesson? Make an illustration that you believe would aid them.

Sources: Most of the information is based on material from David Ewing Duncan's book Calendar: Humanity's Epic Struggle to Determine a True and Accurate Year (Avon, 1998) and Stephen Jay Gould's book Questioning the Millennium: A Rationalist's Guide to a Precisely Arbitrary Countdown (Harmony Books, 1997). William Bennetta and Anne Westwater provided helpful suggestions.