The Explainer: Calendar complexities

That was a scene from Mel Gibson’s “Apocalypto,” where the king and the priests use their astronomical knowledge to impress the faithful. Where there are great powers and great religions, great calendar systems can’t be far behind.

As we embark on our Easter holiday, have you ever paused to wonder why Easter is such a moveable date? Calendars and religion is our topic for tonight. I’m Manolo Quezon. The Explainer.


I. Calendar Power


AS we saw in “Apocalypto,” the great civilizations have been marked by having great calendar systems. The Egyptians, the Persians, the Moslems, the Hindus and the Chinese all had, or have, their great calendars. These are different from the one you and I are used to, both in a secular and religious sense.

But for our purposes tonight, we’re going to tackle the calendars followed in three great historical capitals: Jerusalem, Rome, and Constantinople. The reason we’re going to focus on these three great cities and the calendars that are their historic legacies, is because they’re all connected to the date we celebrate Easter.

Let’s start with why Easter is the greatest celebration in the Christian calendar. Easter marks the commemoration of the Resurrection. And that, as this Holy Week reminds practicing Christians, is the culmination of a profoundly important week in history.

In bold strokes: Jesus entered Jerusalem in triumph on Palm Sunday; on Maundy Thursday, he held the Last Supper; on Good Friday Christ was crucified, died, and was buried; Black Saturday commemorates Christ’s period of being entombed; and Easter Sunday marks the Feast of the Resurrection.

Now you may have wondered why is it, that Holy Week seems to move around from year to year. That’s because the date for Easter changes from year to year; and the reason the date of Easter changes is that in turn, it’s based on a Great High Holiday of the Jewish faith.

That great high holiday is Passover, and to understand our Christian Easter, we have to go back to why it was Jesus was in Jerusalem on the week leading to his crucifixion. He went to Jerusalem to commemorate Passover.

You’ll remember from your Bible stories that Passover commemorates the night Moses was told to smear the doorposts of Jewish families with the blood of a sacrificial lamb. The blood was a signal for the Angel of Death to spare the firstborn of Jewish families. The Angel of Death being sent in the tenth, and final, plague visited upon Egypt since Pharaoh wouldn’t let the Jewish people go.

Now the Jewish faith has its own calendar, the Hebrew Calendar, marked by two things: the way the year and important feasts are calculated, and the manner in which a day begins and ends.

The Hebrew calendar itself , in Jesus’ time, was based strictly on observations of the moon. That is, it’s a lunar calendar. What was tracked was the phases of the moon. The Jewish calendar system depended on a system of two official observers who would identify the new lunar crescent at sunset; this marked the beginning of a new month. Apparently, the tradition was, each new month would be marked by signal fires lit on mountaintops, but after Samaritans started lighting false fires, messengers would be sent.

The Jewish calendar day is sunset to sunset: for example, at sunset on Saturday to sunset on Sunday. The Jewish day is what the Catholic Church follows, for example. Have you ever wondered why you can hear something called an “anticipated Mass,” that is, go to Mass on Saturday night, but it counts for your Sunday obligation? The Jewish day is the reason. By this reckoning, Sunday actually begins on Saturday evening. We also owe the seven-day week to Jewish observance, though their week ended on the Sabbath, that is, Saturday, while Christians end theirs on Sunday.

So how did the Jews determine Passover?

Thus today, for the Jewish faith, Passover begins on 15 Nisan, which in our calendar corresponds to nightfall on April 2; it ends on 21 Nisan, which corresponds to sunset on April 9.

In AD 7_, the Temple in Jerusalem was destroyed in the wake of the revolt of the Jews against Roman Rule. The Arch of Titus in Rome immortalizes the plundering and destruction of the Temple: you can see a frieze of Roman soldiers carrying the great Menorah, or 7-branched candlestick of the Temple as booty in a triumphal procession. By that date, of course, Christianity had been in existence for nearly half a century, and the transition from the center of Christianity from Jerusalem to Rome was taking place.

The shift from Jerusalem to Rome would involve the Easter celebration, also involved a shift from most Christians being originally Jewish, to most of them being Gentiles, or non-Jews. And since the non-Jews who were becoming Christians were inhabitants of the Roman Empire, they in turn were more familiar with another calendar, the Roman calendar.

That Calendar owed its origins to Julius Caesar.

There are two ways.

Lunar calendar.

Solar calendar.



Have you ever read the Pope’s titles? Until recently, this was his full set of titles:

His Holiness the Pope, Bishop of Rome, Vicar of Jesus Christ, Successor of the Prince of the Apostles, Supreme Pontiff of the Universal Church, Patriarch of the West, Primate of Italy, Archbishop and Metropolitan of the Roman Province, Sovereign of the State of the Vatican City, Servant of the Servants of God’


Two of his titles interests us here. The first is “Supreme Pontiff,” and the second is “Patriarch of the West.”

The title of “Supreme Pontiff” is one from Ancient Rome,

In the year 325, after excommunications and thunderous debates, the First Council of Nicaea finally decreed that the Roman timing of Easter would prevail in Christendom.



Last year, Pope Benedict XVI dropped the title “Patriarch of the West,” as a kind of peace-offering to the Eastern Orthodox Churches, which split off from Rome. The Pope’s used that title since AD 450,




By the way, the blog “Whispers in the Loggia” is one of the best guides to the goings-on in Rome, and I’d recommend it for those interested in Vatican affairs.

When we return, the great split in Christendom, and the problem of the date for Easter in the centuries since.


II. As the Romans did


That was a scene from Monty Python’s “Life of Brian.” What did the Romans ever do for us? They also gave us our modern calendar, or to be exact, the Julian Calendar, as we’ve seen.

In ____, a great division in Christianity took place, between ; but until ____, Roman Catholic and Eastern Orthodox Christians celebrated Easter on the same date.


But sometimes, the dates coincide. This year is one of them. As this chart

Shows, Easter on April 8 has been a common one in 1917 and 1928, this year, and again in 2012 and 2091!



Manuel L. Quezon III.

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