The Roman Origins of Our Modern Calendar - Influenced by Popes, Generals, Emperors and Gods

The most widely used calendar around the world today is called the Gregorian calendar. It was introduced by Pope Gregory XIII in the 16th century CE and was a modification of an ancient Roman calendar called the Julian calendar. Even though it is named after a Pope, the Gregorian calendar is very Roman: many of the names of days and months are in honor of Roman, not Christian, deities, and it is the Romans who mostly developed and perfected the calendar that we all use today.    

Pope Gregory XIII, portrait by Lavinia Fontana (Public Domain)

The word calendar comes from the Latin word kalendae meaning the first day of the month. The word kalendae is related to the verb kalare which means to call out, referring to the calling of the new moon each month by the priests of the Capitoline Hill. The first day of the month was also the day debtors had to pay off their debts. These debts were inscribed in an accounting book called the kalendarium. The Latin word was by the 13th century adopted in Middle English as calender, while the spelling calendar (Early Modern English) appeared only centuries later.