VATICAN CITY, 1982, the 4th centenary of the Gregorian Calendar, Scott
716
from a souvenir sheet (see below) and its FDI cancel
GERMANY, 1982, the 4th centenary of the Gregorian Calendar, Scott 1383
SPAIN, 2007, the 425th anniversary of the Gregorian Calendar, Scott
3477 and its FDI cancel
MONTENEGRO, 2007, the 425th anniversary of the Gregorian Calendar,
Scott 155
Clavius was born in Bamberg just before the founding of the Jesuits. He entered the order at age 17, and studied at Coimbra in Portugal and later at the Roman College, excelling in mathematics and astronomy. Clavius taught mathematics at the Roman College from 1564 until 1612. He published profusely — his writings affected the teaching of mathematics in Jesuit schools all over the world — and was the chief mathematician on the commission that led to the Gregorian reform of the calendar. Pope Sixtus V said, "Had the Jesuit order produced nothing more than this Clavius, on this account alone the order should be praised."
The image on the Vatican stamp is from the tomb of Pope Gregory XIII in St. Peter's Basilica. The tomb, the work of Camillo Rusconi, includes a relief showing Clavius kneeling before the Pope, presenting his work as the Pope promulgates the new calendar in 1582. More
The souvenir sheet of the above stamp, Scott 717a