Invented in the 18th century, the perpetual calendar is based on the Gregorian calendar, decreed by Pope Gregory XIII in 1582. It automatically accounts for the 28, 30 and 31-day months, as well as the addition of the 29th of February during leap years. Every hundred years, the Gregorian calendar suppresses a leap year, except during century leap years. Thus, given that 2100, 2200 and 2300 are common years, watches equipped with a perpetual calendar must be corrected by one day on the 1st of March. Among the most difficult complications to achieve, the perpetual calendar is a marvel of micromechanics, representing both a technical challenge for a watchmaker and an inexpressible emotion for any lover of beautiful timepieces. Among the numerous Jaeger-LeCoultre watches with perpetual calendars, the Master Eight Days Perpetual is an iconic model. With its remarkable proportions, this watch offers a clear reading of the perpetual calendar, featuring the month, date, day of the week and year, as well as its power reserve and day/night indicator.