Father Quotes

In the early Church there was no uniform or standard day on which the Resurrection was celebrated, and the First Ecumenical Council at Nicaea decided all Christians should celebrate the Resurrection on the same day. Although not part of any official document produced at Nicaea, the letters written to the churches contained a formula for what day the Resurrection should be celebrated:

This formula gives a unique date for the celebration of the Resurrection, and it was unproblematic for many years. However, it is well-known that the Eastern and Western churches now often celebrate Pascha and Easter on different days (I use the term “Pascha” to be the celebration of the Resurrection by the Eastern churches, and “Easter” to be the celebration by the Western churches). In what follows I raise a puzzle for the common explanation as to why the churches sometimes celebrate Pascha and Easter on different days.

One often hears that although the Western churches and Eastern churches use the same above formula to calculate the dates of Pascha and Easter, when the dates of Pascha and Easter differ it is due to the Western church using the Gregorian calendar and the Eastern church using the Julian calendar. For example, Metropolitan Saba of the Antiochian Orthodox Church recently wrote that both the Eastern and Western churches accept the Nicene formula, and the difference in these dates is due to the calendars used:

“It is a difference in the type of calendar, not in the rule. In the first fifteen centuries, Christians followed what we know as the Old, or Eastern, or Julian calendar. In the Sixteenth Century, Pope Gregory XIII of Rome commissioned an astronomical correction of that calendar, which became known as the corrected, or Western, or Gregorian calendar” [The Word, May -June 2024, p 6].

On this standard view both the Eastern and Western churches accept the Nicene formula, but can get different dates because they use different calendars. Notice that the Nicene formula contains three parts: two of them based on astronomical events (full moon an vernal equinox) and one based on a calendar event (Sunday). This immediately gives rise to a puzzle. The Julian and Gregorian calendars agree on day of the week, so Sunday on the Julian calendar is also Sunday on the Gregorian calendar. But if the only calendar specific part of the Nicene formula is a reference to Sunday, and the Julian and Gregorian calendars agree on what days are Sundays, then how could the different dates of Pascha and Easter be due to the use of different calendars? In other words, if none of the information input into the formula differentiates between the Julian and Gregorian calendars, how can the output be dependent on the calendar used?

Let us restate this puzzle in a different way: the puzzle arises because if the Western and Eastern churches both apply the same Nicene formula, and both the Julian and Gregorian calendars agree on the only calendar dependent part of the Nicene formula, they then should come up with the same dates of Easter and Pascha. The date of the vernal equinox is an empirical astronomical matter, as is the full moon. These are determined empirically and are not dependent on any calendar at all; one could determine when the vernal equinoxes and full moons occur even if one did not have a calendar. So, if people using the Gregorian and Julian calendars agree on when the astronomical events occur, and agree on what days are Sundays, then they should celebrate Pascha and Easter on the same dates. The different dates of Pascha and Easter is not due to the Eastern and Western churches using the same formula but different calendars. It must be due to something else.

To help us get clearer about this puzzle, consider the following experiment. Suppose that archeologists discover original documents from the Council of Nicaea, and in addition to the material on the way to celebrate Pascha, there immediately followed material on what time liturgies should start on Sunday mornings. Evidently members of the Council were concerned that visitors to a town might not know when Sunday liturgy would start, and to avoid any confusion, the Council decided that liturgies on Sundays should start at the same time:

This formula has the advantage that anyone could determine when liturgy would start on a given Sunday. Notice that this formula depends on an empirical event: local sunrise.

Now suppose that at some point the Church declares that sunrise always happens at 6:30 AM local time. Perhaps the Church even calls this “ecclesiastical sunrise” and uses this with the Nicene formula to have all the churches have Sunday liturgies begin at 9:30 AM. In doing this, the church has changed the original Nicene formula. The new formula is

Sunday liturgies should begin three hours after the ecclesiastical sunrise (6:30) AM).

The original formula based starting times on an empirical observable event whereas the modified formula bases starting times on a specific time on the clock, 6:30 AM. Since actual sunrise is not always at 6:30 AM, these formulae can give different times for when Sunday liturgies should begin. It is clear in this example the Church changed the original formula that was given by the Council at Nicaea.

Returning to the dates of Pascha and Easter, the difference is that at some point the Church assumed that the vernal equinox occurs on March 21 of each year on the Julian calendar. This results in a new formula for the date of Pascha:

The first Sunday after the first full moon after March 21 on the Julian calendar.

This is analogous to the Church declaring a fixed time for local sunrise in our thought experiment. In both cases, the Church stipulated an empirical astronomical event happens at a specific day or time. In the case of Pascha, this new formula ties the date of Pascha to a specific date on the Julian calendar, even though the original formula of Nicaea was calendar independent. Notice that one could use the Julian calendar and follow the original Nicene formula; one would base the date of the vernal equinox on empirical matters and not stipulate that it occurs on a certain date on the calendar. If so, churches would celebrate Pascha and Easter on the same day. This explains why the puzzle arises.

Interestingly, in calculating the dates of Pascha and Easter the Churches do not use the astronomical full moon, but instead use an approximation called the “ecclesiastical full moon.” The ecclesiastical full moons do not always correspond with the actual full moons. Thus, in using the ecclesiastical full moon instead of the actual full moon, both the Eastern and Western churches have modified the original Nicene formula.

One might object that fixing the date of the vernal equinox to March 21 is not contrary to what the Council of Nicaea intended, and that members of the Council used the term “vernal equinox” as a way of referring to March 21. I find this implausible. It was clear that the vernal equinox is an empirical matter and astronomers had been able to calculate the date of the vernal equinox for hundreds of years (long before the Julian Calendar). Furthermore, it is not necessary that the vernal equinox occur on March 21 on the Julian Calendar. When Julius Caesar developed the calendar, he designated March 25 to be the vernal equinox. But over the years the date of the vernal equinox had to be pushed back, and by the Council of Nicaea it occurred on March 21. Members of the Council knew this and would have known that in the future the date of the vernal equinox would have to be adjusted. If the Council had wanted March 21 to be a crucial part of the Paschal formula, they would have explicitly mentioned it; instead, they used the term “vernal equinox” to designate a date they knew would not be March 21 in the future.

Notice that the above solution to the puzzle does not claim that the Church has acted improperly in its calculation of Pascha. The point is only that we should not claim that although both the Eastern and Western Churches follow the same Nicene formula, the different dates of Pascha and Easter are due to the use of different calendars. The Nicene formula gives a way to calculate the date for Pascha, and the resulting date is independent of the Julian and Gregorian calendars. The reason the date of Pascha is tied to the Julian calendar is because at some point the Eastern Church modified the Pashal formula given at Nicaea and tied it to a date on the Julian calendar. This is a solution to the puzzle as to why the Eastern and Western churches often celebrate Pascha and Easter on different dates.

However, this is the 1,700 anniversary of the First Ecumenical Council, and the topic of the dates of Pascha and Easter are under discussion. Recently Pope Francis expressed his desire for “all Christians to take a decisive step forward toward unity around a common date for Easter.” If the Eastern and Western churches are genuinely interested in having a common date of Pasha/Easter, I propose the following:

Return to the original formula given by the Frist Ecumenical Council.

On this proposal, the date of Pascha/Easter would be based on the first Sunday after certain astronomical events; there would be no calendar-dependent parts, nor would there be any dependency on any estimates of these astronomical events. It is now fairly easy to determine and predict vernal equinoxes and full moons, so no calendar or estimates are needed. Both the Eastern and Western churches would have to make changes upon this proposal. I realize that changing the calculation of Pascha/Eater would be neither quick nor easy, but during this 1,700 anniversary of the First Ecumenical Council, it would be especially fitting to return to the original Nicene formula and for all Christians to celebrate the Resurrection on the same day.