XJUUS
248
LILIU8
Of Lilius's life nothing is known beyond the fact that
he was professor of medicine at the University of
Perugia as early as 1552. In that year he was recom-
mended by Cardinal Marcello Cervini (afterwards Pope
Marcellus II) for an increase of salary as an eminent
professor and a man highly esteemed by the entire
university. This date may explain why Lilius did not
live to see his calendar introduced thirty years later.
The statement in Pog^endorff's " Handworterbuch",
that Lilius was a physician in Rome and that he died
in 1576, is apparently not supported by recent re-
searches. In that year, 1576, nis manuscript on the
reform of the calendar was presented to the Roman
Curia by his brother Antonius^ likewise doctor of arts
and m^icine. Antonius was probably many years
younger, as he survived the reform and owned the
copyright of the new calendar, until, by retarding its
introduction, he lost that privilege, and its printing
became free. Mention is made of a Mgr Thomas
Giglio, Bishop of Sora, as first prefect of the papal
commissions for the reform. If lie was a relative of
the two brothers, he was not guilty of family favourit-
ism, as he proved himself an obstruction to Aloigi's
plans. Lihus's work cannot be understood without a
Knowledge of wliat was done before him and in what
shape his reform was introduced.
Gbegorian Reform of the Calendab. — From the Council of Niccea to that of Constance. — ^The reform of the'calendar was from the start connected with general councils, viz. those of Nicaea (325), of Constance (1414 -1418), of Basle (1431), the Fifth of the Lateran (1512-1517), and that of Trent (1545-1563). The double rule, ascribed to the first council, that the ver- nal equinox shall remain on 21 March, where it then was, and that Easter shall fall on the Sunday aft«r the first vernal full moon, was not respected by all those that planned reforms, but was stnctly adhered to in the Gregorian Calendar. It was well known, at the time of the Council of Nicaea, that both the Julian year and the lunar cycle of Meton were too long; yet a remedy could not be adopted until the errors were more exactly determined. This state of knowledge lasted throughout the first twelve hundred years of our era, as is testified by the few representatives of that period: Gregory of Tours (544-595), Venerable Bede (c. 673-735). and Alcuin (735-804). Some progress was made aurin^ the thirteenth centurv. In the "Computus" of ^uigister Chonrad (1200) the error of the calendar was again pointed out. A first approxi- mation of its extent was almost simultaneously given by Robert Grosseteste (Greathead, 1175-1253), Chan- cellor of Oxford and Bishop of Lincoln, and by the Scottish monk Joannes a Sacrobosco (Holvwood or Halifax) . According to the former one leap day should be omitted ever>' 300 years; according to the latter 288 Julian years were just one day too long, and 19 Julian years were one and one-third hours snorter than the lunar cycle. While the latter error is estimated cor- rectly, the other two numbers 300 and 288 should be re- placed by 128. The Franciscan friar, Roger Bacon of Ilchester (1214-1294), basing his views on Grosseteste, recommended to the pope a series of reforms, the merits of which he did not decide. Campanus (be- tween 1261 and 1264) made to Urban IV the specific proposition to replace the lunar cycle of 19 years by two others of 30 and 304 years. The most important step in the thirteenth centur}' was made by the ap- pearance, in 1252, of the astronomical tables of King Alplionsus X of Castile.
The fourteenth century is remarkable for an astro- nomical conference held at the papal court in Avignon. In 1344 Clement VI sent invitations to Joannes de Muris, a canon of Mazi^res (Canton Bourges), who was held to be no mean astronomer, and to Firminus de Bella valle (Beauval), a native of Amiens, and others. The result of the conference was a treatise written by the two authors just mentioned: "I^istola super re-
formatione antiqui Calendarii. It had four parts: the
solar year, the lunar year, the Golden Number, Easter.
A third author was the monk Joannes de Thermis.
Whether he was a member of the same conference or
not, certain it is that he was charged by Clement VI to
write his Tractatus de tempore celebrationis Pas-
chalis'\ It appeared nine years after the conference
(1354) and was dedicated to Innocent VI, successor to
Clement VI. In the same centurv other treatises on
the errors and the reform of the calendar are recorded,
one of Magister Gordianus (between 1300 and 1320)
and one of a Greek monk, Isaac Argyros (1372-3).
The Councils of Constance and Basie, — ^The fifteenth century marks an epoch in the reform of the calendar by two scientific authorities, Pierre d'AiUy and Nico- las de Cusa, both cardinals. Pierre d'Ailhr (1350- 1425), Bishop of Cambrai and Chancellor of the Sor- bonne, followed the views of Roger Bacon. After advising Pope John XXIII in 1412, he pointed out to the Council of Constance, in 1417, the great errors of the calendar. He suggested different remedies: first, to omit one leap day every 134 years, thereby correct- ing the solar year; second, to omit one day of the lunar cycle every 304 years: or third, to abandon all cyclical computation and follow astronomical observa- tion. It must be noticed that the first and third proposition of Cardinal d'Ailly are reiterated in our own days (substituting for 134 the correct number 128). The first and second of d'Ailly's propositions were elaborated and again proposed by Caniinal de Cusa a401-1446) to the Council of Basle. The error should be corrected by omitting 7 days in the solar cycle (passing, in 1439, from 24 May to 1 June) and 3 days in the lunar cycle. His *' Reparatio Calendarii" furnished much information to subsequent reformers. He was the first to take into account differences of longitude for various meridians. The two councils wisely postponed the reform of the calendar to some future time. The fifteenth century was not to cloee, however, without considerable progress connected with the names of Zoestius, John of Gmund, George of Pur- bach, and John of Koenigsberg (Regiomontanus). A treatise on the reform of the calendar by Zoestius ap- peared after 1437. The first printed almanacs were issued by John of Gmund (d. 1442), dean and chan- cellor of the University of Vienna. His disciple was Purbach, afterwards professor of mathematics at the same university and teacher of John Milller, called Regiomontanus aft^r his native place in Franken. The latter (1435-1476) continued the work of the chancellor in publishing calendars that served as models for a century to come. The Golden Numbers of the lunar cycle were retained, but the lunations were taken from observation. This combination made the errors of Easter more and more manifest. Regio- montanus was called to Rome by Sixtus IV^ for the purpose of reforming the calendar, but died shortly after his arrival at the age of fortv-one.
The Councils of the Lateran and of Trent, — The two councils of the sixteenth century were finally to pave the way for the long desired reform. The efforts tnade at the Lateran Council are described by Marsi. From the twelve or more authors enumerated by him it will suffice to mention the two that exercised a decisive in- fluence: Paul of Middleburg, who started the proceed- ings, and Copernicus, who brought them to a tempo- rarv conclusion. The life of the former is described by Bnldi in Appendix I to Marzi. Paul bom in 1445, died as Bishop of Fossombrone in 1534. He was called from Louvain to Italy by the Republic of Ven- ice, became professor of mathematics at Padua, and physician and astrologer to the Duke of Urbino. B^ tore the opening of the council in 1512 he asked JuliusII to attend to the calendar. Leo X sent out briefs to Maximilian I, the princes, bishops, and universities, to obtain their opinion on the calendar, and appointed the Bishop of Fossombrone as president of the oooi-
