Luigi Lilio: the scholar behind our calendar

Luigi Lilio, also known as Luigi Giglio and in Latin sources as Aloysius Lilius, was a physician and scholar of mathematics and astronomy of the Renaissance. A native of Cirò in Calabria, he was probably born around 1510. His death is generally placed in 1576, before the implementation of the reform with which his name is associated.

Information about his life is fragmentary. The biographical tradition recalls medical studies in Naples and an intellectual path in which an interest in the measurement of time took on a central role. Reconstructing his education, his movements and his scientific relationships still requires a careful comparison of documents and testimonies.

A problem that concerned the whole of Europe

Lilio tackled a question that had been debated for centuries: how to correct the Julian calendar and make the calculation of Easter more reliable. His proposal coordinated the correction of the solar year with a system of tables and rules for the lunar computation.

After his death, his brother Antonio presented the project to the papal authorities. Examined and discussed during the preparatory work, it formed the basis of the reform promulgated by Gregory XIII in 1582.

The Luigi Lilio International Study Centre promotes knowledge of his work through documentary research, mathematical study and outreach, distinguishing documented evidence from reconstructions that remain to be verified.