Aloisius Lilius

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Aloisius Lilius

Aloisius Lilius (* around 1510 in Cirò , Calabria , † 1576 probably in Rome ), actually Luigi Lilio or Giglio or Aluise Baldassar Lilio, was an Italian physician , astronomer and philosopher . He is considered to be the spiritual author of the Gregorian calendar .

All that is known of Lilius' early life is that he was a doctor, after having graduated from Naples, where he also studied astronomy, moved to northern Italy (Verona) and taught at the University of Perugia in 1552 . That year, Cardinal Marcello Cervini, who later became Pope Marcellus II , recommended him as an excellent and highly respected professor for a salary increase.

In a manuscript that is now lost, Lilius made a proposal for calendar reform, which his brother Antonio, the Pope's personal physician, was the expert of Pope Gregory XIII. 1575 presented, to which u. a. the mathematicians and astronomers Christophorus Clavius , Pedro Chacón (1526–1581), Ignazio Danti and the Cardinal Guglielmo Sirleto belonged. Lilius died soon afterwards in 1576. The Compendium novae rationis restituendi kalendarium , written by Chacón for the Congregation of Experts, contains a summary of Lilius' work. Clavius ​​had it printed and sent in 1577 to all Christian princes and universities for examination by competent scientists. As a core element it contains Lilius' new nineteen-year cycle of epacts . Eventually the Calendar Congregation adopted Lilius' design with only minor changes. The papal bull Inter gravissimas , with which the calendar reform was ordered in 1582, expressly mentions Lilius as its author.

His brother Antonio initially received the sole right to print the new calendar in the Papal States, but this was withdrawn from him during the introductory phase because he could not deliver in sufficient numbers.

The lunar crater Lilius and the asteroid (2346) Lilio are named after him.


  • Giulio Armolo: Papi - Astronomi - Epatte, Luigi Giglio , Naples 1963 (biography)
  • Jacques Dutka: On the gregorian revision of the Julian Calendar , Mathematical Intelligencer 1988, No. 1 (with portrait of Lilius)
  • August Ziggelaar: The papal bull of 1582 promulgating a reform of the calendar , GV Coyne, MA Hoskin, O. Pedersen: Gregorian Reform of the Calendar: Proceedings of the Vatican conference to commemorate its 400th anniversary. Specola Vaticana, citta del vaticano 1983 (on Lilius p. 206)

Web links

Individual evidence

  1. Josef Schmid On the history of the Gregorian calendar reform , yearbook Görres Gesellschaft 1882, 389. Ziggelaar (see literature) states, however, that he did not find anything of the kind in the source from the Vatican library given by Schmid