The second prime mover was the Jesuit astronomer Christopher Clavius (1538-1612), the man behind the scenes who championed Lilius’s ideas (after an initial scepticism) and shepherded the reform through the minefields of scientific and ecclesiastic controversy before and after 1582. Until he died in 1612, Clavius worked hard to defend and explain the new calendar, ensuring that it would spread beyond the handful of countries that initially accepted it.
As a prominent public figure in Rome during the late sixteenth and early seventeenth centuries, more is known about Christopher Clavius than about Lilius. Yet little exists to flesh out who he really was. In a portrait of Clavius rendered in 1606 he is dressed in a simple Jesuit robe and a four-cornered hat. A portly, satisfied-looking man with a pudgy, bearded face, he looks sympathetic, even kind--the sort of scholar who is serious but never stuffy, smart but not precocious; one that students are fond of, and one that politicians and prelates feel comfortable assigning to commissions.
To his contemporaries Clavius was a revered sage of maths and astronomy, acclaimed as ‘the Euclid of his times’ in part because he penned a widely used translation of the original Euclid, along with several other works considered important in his day. Even the era’s greatest scientific firebrand, Galileo Galilei, came to him for validation of his telescopic observations of the moon, sun and planets. Clavius hailed them as important to astronomy, but since he was a confirmed defender of Ptolemy he disagreed with Galileo’s interpretation that craters on the moon, Venus passing through its phases, and moons around Jupiter suggested Copernicus was correct. Clavius also has the distinction of having his face inscribed on a marble relief on the base of Gregory XIII’s imposing statue in St Peter’s (probably Clavius) which shows a priest handing the pope a copy of the calendar reform.
Yet Clavius today is nearly as obscure as Aloysius Lilius. In part this comes from the bad luck to have lived between Copernicus--Clavius was five years old when De revolutionibus was published--and the young Galileo, who burst onto the scene in Clavius’s final years. But more than anything, Christopher Clavius is obscure because he adhered to a world view that turned out to be wrong. This made him a hero to traditionalists while he was alive, but a fool to those who came later.
Clavius was surprisingly young when Pope Gregory named him to his new calendar commission, convened in the mid-1570s. Born on 25 March 1537, in the Bavarian town of Bamberg, Clavius’s life to us is a blank page until he joined the recently formed Society of Jesus--the Jesuits--in Rome on 12 April 1555. Studying in Rome and then at the University of Coimbra in Portugal, Clavius returned to Rome in the early 1560s to finish his education and then to teach at the Jesuits’ own Collegio Romano, where he became a professor of mathematics. But for a few short trips, he would remain in Rome until his death.
As a mathematician and astronomer, Clavius was a minor figure, notable mostly for his work on Euclid, algebraic notation and the calendar--and for his staunch defence of an earth-centred universe. Yet Clavius was flexible enough to constantly update his own theories to incorporate Copernican data and Galileo’s observations, attempting to squeeze it into an increasingly strained Ptolemaic interpretation.
Clavius’s willingness after 1582 to at least consider new ideas as Rome’s senior astronomer seems to have exercised a restraining influence on the inevitable showdown between the ideas of Copernicus and those of Ptolemy, primarily benefiting the young Galileo, whose reputation was enhanced by Clavius’s support of his telescopic discoveries. Galileo judged Clavius to be ‘worthy of immortal fame’, and forgave him for rejecting the Copemican theory, a shortcoming he blamed on the old man’s age.
Others were not so forgiving. In 1611 the England poet and satirist John Donne (1572-1631), a former Catholic in this sometimes virulently anti-Catholic kingdom, penned a vicious satire of the Jesuits and their founder, Ignatius Loyola (1491-1556), titled Ignatius His Conclave. Donne describes Loyola in hell trying to convince Satan to reject Copernicus because the Polish astronomer had not done enough to obfuscate the minds of men and therefore keep them from the truth. In the midst of this the poet mentions Clavius, whom he could not place in hell because in 1611 the old astronomer was still alive. But Donne did have his Loyola tell the dead Copernicus about a candidate possibly more ‘worthy’ for the netherworld, describing among other things Clavius’s work on calendar reform, which the English, as Protestants, considered tainted because it came from Rome:
If therefore any man have honour or title to this place in this matter, it belongs wholly to our Clavius* who opposed himselfe opportunely against you, and the truth, which at that time was creeping into every man’s minde. Hee only can be called the Author of all contentions, and schoole-combats in this cause; and no greater profit can bee hoped for heerein, but that for such brabbles, more necessarie matters bee neglected. And yet not onely for this is our Clavitis to be honoured, but for the great paines also which hee tooke in the Gregorian Calendar, by which both the peace of the Church, and Civill businesses have beene egregiously troubled: nor hath heaven it selfe escaped his violence, but hath ever since obeied his apointments: so that S. Stephen, John Baptist, & all the rest, which have bin commanded to worke miracles at certain appointed dates ... do not now attend till the day come, as they are accustomed, but are awaked ten daies sooner, and constrained by him to come downe from heaven to do that businesse.
*This is a satirical use of the name given to Clavius by the Jesuits, who called him ‘our Clavius’.
The final person in our troika was born Ugo Buoncompagni (1502-1585). The son of a noble family in Rome, he became a prominent ecclesiastic lawyer and senior papal official before being elected Pope Gregory XIII at age 70, on 14 May 1572. One of several pontiffs in the sixteenth century who worked to rebuild the authority of the Church and to reform its worst excesses, he was zealous in trying to stamp out Protestantism, chiefly by lavishing money on building up Catholic colleges across Europe, and by launching Church reforms in Germany, Poland and Belgium. He also dispatched Jesuit missionaries to countries such as India, the Philippines and China, where European ships had begun to sail with some regularity.
But Gregory also suppressed knowledge that failed to agree with Church dogma, establishing an infamous index of banned books that later listed Copernicus’s De revolutionibus. He also supported military efforts by Catholic monarchs against Protestants, and connived in attempts to undermine England and Queen Elizabeth I--including ill-conceived military ventures to thwart English efforts to conquer and dominate Ireland. But all this pales against Gregory’s infamous response to the slaughter of thousands of Huguenots in Paris that began on St Bartholomew’s Day, 1572. Hearing the news, the newly installed pope is said to have ordered a Te Deum--a hymn of praise to God--and issued a medal.*
*Catholic apologists insisted he did so without knowing the extent of the massacre, and that he actually wept when he heard the truth.
In Rome Gregory supported grandiose building projects; he also was known as a man who enjoyed pomp and celebration, nearly bankrupting the Vatican treasury with his edifices and fetes. His tenure as ruler of the papal state--a swath of land running across the middle of Italy and governed directly by the Vatican--was marked by peasant riots over steep taxes and by a rise in banditry and lawlessness, which he proved incapable of stopping.
But most of this has been forgotten, with Gregory chiefly remembered as the pope who finally corrected time, a feat that begs the question: why this pope?
Probably his motivation came from the same zeal he devoted to promoting education and putting the Church back onto a more sound intellectual track. But it also came from the lawyer Ugo Buoncompagni’s systematic attempts as pontiff to enact reforms approved by the various church councils, particularly those passed at the various sessions of the Council of Trent (1545-1563), where Buoncompagni served as Pius IV’s deputy and may have drafted some of the decrees. One of these ordered the reissuance of the mass book and breviary--the Catholic list of da
ily hymns and ceremonies--which implied the need for an updated calendar. Indeed, the first words in the momentous 1582 bull announcing the calendar reform do not claim the authority of science, the Church or even God, but the decree of Trent, as if this legalistic sanction mattered most to this old lawyer-pope:
Among the most serious tasks,* last perhaps but not least of those which in our pastoral duty we must attend to, is to complete with the help of God what the Council of Trent has reserved to the Apostolic see.
*Like all bulls, this one was named after its opening lines. In Latin, this has been shortened to Inter gravissimas.
As the pace of reform quickened, the story of the calendar returns to the same city where Julius Caesar had launched his calendar 16 centuries earlier--though it could hardly have been more different.
Rome in the sixteenth century had ceased long before to be important as a commercial, political or intellectual centre. Nor did the Roman Church wield the all-embracing authority it once had enjoyed as Europe’s religious overlord, now that Protestantism had broken up its monopoly of the spirit, and kings and princes had eclipsed its influence in the realms of politics and finance. Still, the Church remained the only force in Western Europe capable of exerting anything like a universal authority. It also had been the guardian of the calendar for centuries, for better or for worse, and was now riding a certain momentum from years of reform talk and council decrees aimed at making a fix.
Rome itself in the 1570s looked ruined and exhausted, its ancient monuments, palaces and temples shattered and half buried by dirt and rubbish, its ancient walls and columns picked apart for centuries and incorporated into a disconcerting hodgepodge of old and new. Even the once mighty Forum, where 16 centuries earlier Caesar had stood up to announce that he was establishing a new calendar, was now called the Campo Vaccino, the ‘Cow Pasture’. Buried under eons of trash and dust, and mostly dismantled for its marble and bricks, this place that had been the centre of the Roman world was now the domain of bovines chewing tufts of grass growing around broken columns and archways.
The Eternal City that Clavius and Gregory lived in during the years of the calendar commission stood inside the sprawling ancient walls built in the third century by Emperor Aurelian. Diminished now from as many as a million people in imperial times to perhaps sixty thousand--though in the 1570s it was beginning to grow again--the city’s inhabited areas were clustered near the Tiber, where those who stayed through the barbarian invasions had moved for easy access to water after the aqueducts were cut. This left large sections inside the walls empty of people. These vast stretches of space were used for vineyards, gardens, garbage dumps and pastureland, and were marked here and there by scattered farmhouses and convents. Forests grew on the slopes of the Palatine, Caelian and Aventine Hills. Deer and boar ran wild amidst the ruins of ancient villas covered with ivy and trees in which hundreds of pigeons squawked and fluttered.
Because of the water problem and the location of St Peter’s near the river, Rome’s centre had shifted north from the Forum to the C-shaped bend in the river between the Capitoline Hill to the south (just above the Forum-turned-pasture) and the Piazza del Popolo to the north-west. Still very much a medieval city, Rome in those days was a confusing knot of narrow, winding, fetid streets filled with people, animals, dung, dust and sewage and edged by brick houses, shops, stalls and offices. This was broken up here and there by piazzas and by a scattering of new Renaissance churches, including St Peter’s Basilica with its half-finished dome by Bramante and Michelangelo. Rome’s fractious noble families had recently erected a number of splendid new palaces and villas, many of them on hills with breath-taking views of the city.
Another new building project was an extensive upgrading of Christopher Clavius’s own Collegio Romano, which Gregory XIII took on as part of his efforts to improve Catholic universities. He lavished funds and support on the previously struggling Collegio, in part because of his close ties to his favourite astronomer, who made a special pitch for improvements in the departments of mathematics and astronomy.
The pope’s attention to Roman education was long overdue. Before his improvements, the Collegio Romano had been one of two clearly second-rate outposts of learning in a city known for raucous local politics, pilgrimages, indulgences and papal fetes, but not for intellectual pursuits. Rome in the 1570s still lacked any meaningful tradition of universities and scholarship. Nor did its officials offer much public support for scientific or technical research--unlike cities such as Florence, where the ruling Medicis hired Galileo as their court mathematician in 1610, or the Holy Roman Imperial court, which commissioned the astronomers Tycho Brahe (1546-1601) and later Johannes Kepler (1571-1630) to advise Emperor Rudolph II of Bohemia.
In the lovely Tuscan village of Siena is a painting of Pope Gregory XIII crowned and enthroned, leaning forward and listening intently to a scholar on the calendar commission describe the error in Caesar’s calendar. This man looks like Clavius as depicted when he was older, with a white beard and four-cornered hat. Pointing to a picture of the zodiac on the wall he is explaining to the pope the difference between the Julian calendar, marked on a band outside the zodiac, and the true seasonal year, portrayed on the inside. He stands amidst members of the commission, some of whom are dressed in the flowing robes, broad-brimmed hats and priestly hoods popular at that time in Italy. Seated around a table, the commission is surrounded by books and astronomic tools, including an armillary sphere the scholarly speaker is manipulating with his left hand as he points to the zodiac chart with his right.
The names of the members of the commission that worked through the 1570s and early 1580s were not recorded, except in the final report presented in 1581 to the pope--which is probably the meeting depicted in the Siena painting. Nine individuals signed this report, presumably all of them members of the commission, though one seems to have been simply a witness. The signatories included a cardinal, a bishop, a former Syrian patriarch, a man from Malta, a French lawyer, a Spanish historian and theologian, a physician and two scholar-scientists.
The cardinal and the bishop were senior church officials now all but forgotten. They are Cardinal Guglielmo Sirleto (1514-1585), a scholar, Hellenist and contender for the papacy, who served as president of the commission, and Bishop Vincenzodi Lauri of Mondovi. Why they were chosen is unknown, though in Sirleto’s case the appointment of someone so senior and respected was clearly a signal by the pope to the Vatican bureaucracy and to everyone else within the Church that Gregory was serious about reform. Sirleto and Lauri may also have been experts on the Church calendar and its history, and on the deliberations of Church councils.
The patriarch was Ignatius of Antioch, a Jacobite Christian from Syria who had arrived in Rome in 1577 or 1578 to seek a personal reconciliation with the Roman Church. A refugee from the still-mysterious East whom some suspected was a fake--until he was confirmed as genuine--Ignatius was knowledgeable in mathematics and medicine, and he brought to the commission an Eastern perspective on astronomy and the calendar. He provided Clavius and the scientists with useful comments on their proposed reforms, written in Arabic and translated into Latin. He signed the 1581 report in Arabic and Syriac.
The man from Malta, Leonardo Abel, seems to have signed the final report just to serve as a witness to Ignatius’s signatures, apparently because he was fluent in Arabic. The French lawyer signed his Latinized name as Seraphinus Olivarius Rotae, an auditor Gallus who may have been summoned to help the commission sort through the many legal implications of the reform for both canon and civil law. The Spaniard was Pedro Chacon, who probably advised the committee on past and present papal and Church pronouncements on the calendar, and on the critical issues of Easter and saints’ days. He also authored some of the key documents of the commission.
The scholar-scientists included the Dominican friar Ignazio Danti (1536-1586), the second most famous commission member after Clavius. A mathematician, astronomer, cartographer and artist, Danti was
a professor of mathematics at Pisa and later at Bologna.
Summoned to Florence he also worked on astronomic projects under Grand Duke Cosimo I (Cosmos de Medici), preparing maps, an enormous terrestrial globe and instruments he used to observe the vernal equinoxes in 1574 and 1575. From this he came up with the length of the year as 365 days, 5 hours and 48 minutes. Comparing this to Ptolemy’s erroneous calculation of 365 days, 5 hours and 55 minutes, Danti joined Copernicus and other astronomers by concluding that the tropical year was variable. After a falling-out with Cosimo’s son, Danti relocated to Bologna, where he measured the solstices in 1576 with a gnomon he built in the church of St Petronius. He used this data to confirm the error in the Julian calendar and its drift against the true year.
In 1580 Danti was summoned to Rome by the pope to join the commission, and also to design the frescoes and astronomic instruments in a new building devoted to astronomy and to calendar reckoning. Known as the Tower of the Winds, this 240-foot tower north of St Peter’s dome and above the Vatican archives, was built between 1578 and 1580 and decorated with Danti’s designs between 1580 and 1582. These included a series of enormous frescoes of the four winds, rendered in the style of Titian as voluptuous cupids flanked by images of astronomers at work. Danti also equipped the main room of the tower with an enormous anemometer (wind gauge) attached to a weather vane. He etched into the floor a map of the stars and zodiac, situated so that a small hole in the wall would shine a ray of sunlight onto the map, varying according to the seasonal angle of the sun. This created in the Tower of the Winds a crude seasonal calendar. In 1583, after the reform, Danti was named bishop of Alatri in Italy, where he died in 1586.
The Calendar Page 24