It’s Leap Year, & Here’s Why! February 24, 1582: Pope Gregory XIII Issues the Proclamation, Inter Gravissimas, & A Commentary by Fr. Richard Kunst

February 24, 1582: Pope Gregory XIII Issues the Proclamation, Inter Gravissimas, Resulting in the Gregorian Calendar Replacing the Julian Calendar

The artifact presented here is interesting in that it was signed by Pope Gregory XIII and is dated February 9, 1581, prior to the enactment of the Gregorian calendar, which occurred on Thursday, October 4, 1582.

Historically, the Catholic Church has been a major sponsor of astronomy, not least due to the astronomical basis of the calendar by which holy days and Easter are determined.

The Church’s interest in astronomy began with purely practical concerns, when in the 16th century Pope Gregory XIII required astronomers to correct for the fact that the Julian calendar had fallen out of sync with the sky. Since the spring equinox was tied to the celebration of Easter, the Church considered that this steady movement in the date of the equinox was undesirable.

The resulting Gregorian calendar is the internationally accepted civil calendar used throughout the world today and is an important contribution of the Catholic Church to Western Civilization.

It was introduced by Pope Gregory XIII, after whom the calendar was named, by a decree, a papal bull, Inter Gravissimas, signed on 24 February 1582.

Father Richard Kunst, Curator & Commentator

Every Four Years, Thank Pope Gregory XIII for an Extra Day

Something happens only once every 1,460 days. I am, of course, referring to leap day, Feb. 29.  While not occurring this year, it’s interesting to reflect upon its origins.

It’s easy to remember which years have 366 days because they coincide with presidential elections, although I am sure there is no connection between the two.

Leap year and leap day are not simply calendar oddities. They point to the influence of the Catholic Church on civilization. Until the 16th century, most of the world was using the Julian calendar, which had been established in 45 BC by the Roman Emperor Julius Caesar. The Julian calendar year was 365.25 days. Due to inaccuracies in this system, three days were gained every 400 years.
Over the centuries, people discovered the Julian calendar was becoming inaccurate simply by looking at the moon. By the 16th century, the lunar calendar was out of whack with the real moon by four days.

This had an effect on the church’s celebration of Easter, which, according to the Council of Nicaea in AD 325, had to be based on the vernal equinox. That was believed to be March 21, but due to the inaccuracies of the Julian calendar, the real lunar calendar started to affect Easter’s dating. Enter Pope Gregory XIII.

The science behind the formation of the calendar is much more complex than this, but suffice it to say it was Pope Gregory XIII (1572-1585) who, on Feb. 24, 1582, decreed in the papal bull “Inter gravissimas” that the calendar would be reformed later that year. By that time, the accumulated error over the centuries meant there were 10 days too many on the calendar. By the authority of that papal bull, the last day of the Julian calendar was Thursday, Oct. 4, 1582, while the first day of the Gregorian calendar — the very next day — was Friday, Oct. 15, 1582

The exact Gregorian reform means that every year exactly divisible by four is a leap year, with the exception of the years that are divisible by 100. In those century years, only the ones that are exactly divisible by 400 are leap years. So the year 1900 was not a leap year, but the year 2000 was, because it was divisible by 400.
Although not everyone adopted the Gregorian reforms right away, it did not take long before the whole world went along with them. The last holdouts were Russia and Greece. They did not adopt the Gregorian calendar until the 20th century, and when they did, they had to drop 13 days from their calendar to do it. For some of their movable feasts, the Orthodox Church still observes the Julian calendar, but apart from them, almost all of civilization has a calendar named after the pope who promulgated it.
The calendar reforms of Pope Gregory XIII are tangibly seen in St. Peter’s Basilica. Several popes have large and impressive funerary monuments on the main floor of the basilica, and each monument has depicted on it the scene or episode for which that pope was most noted. On the actual sarcophagus of Gregory XIII is shown the scene of astronomers pointing out their discoveries to the pope, the discoveries, which were later named for him.

There is a very interesting aside to all this information on the calendar reforms instituted by the church. Most often, the Catholic Church celebrates saints’ feast days on the anniversary of the day the saint died because that it is the date on which they accomplished their mission of salvation. We celebrate birthdays; the church celebrates death days! Well, the Carmelite saint and doctor of the church Teresa of Avila was dying the night of Oct. 4, 1582. She died at the stroke of midnight (or very close to it), so her feast day is Oct. 15, the very next day, the first day of the Gregorian calendar.

Whenever you hear the term “Gregorian Calendar” being used, know that it is a point of influence of the Catholic Church and its popes. The church has had, and continues to have, influence over all aspects of Western Civilization, so much so that every calendar you own, whether it is on paper or on your iPad, is thanks in part to Pope Gregory XIII. Happy Leap Day!

About the Medal: Pope Gregory XIII’s image is on one side and an image of him opening the Holy Year door is on the reverse side.

Pope Gregory XIII:

Era: 1572-1585

Ugo Boncompagni was born in Bologna in 1502, the fourth son of a merchant and an aristocratic mother. He was educated at the University of Bologna, earning a doctorate in law. For the next eight years he remained there as a law professor.

Boncompagni had already received minor orders when, in order to carry on the family name he had a son, Giacomo. When he was about forty years of age he went to Rome, was ordained a priest and entered the papal service. Paul III, aware of his skills both in law and administration provided him with a series of responsible judicial posts. Paul IV appointed him a commissioner for church reforms as well as gave him diplomatic missions.

From 1561 –1563, due to his legal skills, he played a considerable part in drafting decrees at sessions of the Council of Trent. Pius IV made him a cardinal in 1565. He was sixty-three years of age. As the papal legate to Spain he became acquainted with and was trusted by Phillip II.

It was largely due to the influence of Phillip II that Cardinal Boncompagni became the next pontiff upon the death of Pius V in May of 1572. Within twenty-four hours he was elected after Phillip II withdrew his support for a rival candidate paving the way for Boncompagni to become Gregory XIII.

The double role of the papacy—the temporal and spiritual—created many and varied areas of responsibility for the new pope. Both politically and spiritually one of the first matters to affect his reign came to be known as The St. Bartholomew’s Day Massacre in August of 1572. His name will be forever associated, though somewhat unfairly, with that event. This matter concerned the brutal murder of at least 4000 French Protestants, known as Huguenots, at the behest of Catherine di Medici and carried out by Charles IX. This event shattered any hope of reconciliation between the Protestants and the Catholic Church. Gregory XIII had no prior knowledge of this event and wept bitterly over the carnage incurred there. His decision to hold a service in Rome commemorating the victory was actually more about another event where an assassination attempt on the life of Charles IX was averted. It was not about approving the butchery of thousands of Christians, although this is, unfortunately, how it is remembered.

There is no way to justify what Hans Kuhner in The Popes has called the universal hysterical joy on the Catholic side…that shows the unprecedented psychic brutalization of the times. Furthermore, Kuhner states, it was almost impossible for him to maintain a clear line (of information and understanding) during the religious wars following that horrible night of massacre in Paris amid the chaos of all the atrocities that occurred on both sides.

Another political mistake he made was approving through his Secretary of State, the assassination attempt on the life of Elizabeth I of England and the pestering of Spain’s Philip II to invade England to accomplish this.

Despite his lack of political acumen or of successful financial policies, Gregory XIII still contributed to the papacy in myriad ways during the twelve years of his reign. Of great significance was the replacement of the inaccurate Julian calendar with what came to be known as the Gregorian System, still in use after five centuries. The new calendar struck ten days in October off the existing calendar thereby giving it the accuracy it needed. Catholic countries followed it immediately and by the 1700’s even England had adopted the calendar.

The calendar was considered to be his most significant accomplishment but Gregory was responsible for so much more. He continued to promote the reforms of the Council of Trent and was influenced by Charles Borromeo in this work. He was the first pope to use a Secretary of State in the modern sense. He appointed a commission of cardinals to oversee the bishops to ensure they resided in their dioceses. He sought to use nunciatures as instruments of reform rather than just as diplomatic missions, and in this spirit he created new ones.

One of Pope Gregory’s most significant contributions was his awareness that a well-trained clergy was key to spreading the Catholic faith and to recovering all that had been lost during the Protestant Reformation. His belief that real reform would only come in this way and never through punitive means propelled him to establish twenty new colleges in different countries to educate men for the priesthood. These included the endowment in 1572 of the Roman College (later Gregorian University), run by the Jesuits, and the many others he endowed in different countries.

Gregory supported missionary work in India, Japan, China and Brazil, as well as in Northern Europe where repeated efforts to reconcile with the Church in Sweden were unsuccessful. A particularly memorable event in his papacy was the arrival of the envoys from Japan who visited the Holy Father to pay him homage, an event over which he was highly delighted.

Another contribution he made was sanctioning the reform of the Carmelites by Teresa of Avila (1515–1582). Others who received his special favors were Charles Borremeo, Phillip Neri and Robert Bellarmine, all who were later canonized. Additionally, he refined the body of canon law in 1582, was a proponent of archaeology and understood the importance of preserving the Roman catacombs. He built many famous edifices including churches and fountains and the beginning of a summer residence. During his papacy, the Jubilee Year of 1575 was celebrated in splendor due to his renewal of Rome.

All of these expenses, however, created other problems. In his later years there was widespread lawlessness when he confiscated, albeit legally, land which nobles were reluctant to part with. This created immediate problems for his successor, Pope Sixtus V.

Gregory XIII died in April of 1585. He was buried in the Chapel of St. Peter, hitherto called the Gregorian Chapel.