Joseph Ratzinger was ordained a priest on 29 June 1951, the Feast of Saints Peter and Paul. This year marks the 60th anniversary of that key moment in his journey of faith. The Philatelic Office is dedicating a series of four stamps for this special occasion. The most important moments in his life as a man of the Church are depicted on each stamp, next to symbols present in his papal coat of arms. His priestly ordination is accompanied with the symbol of a shell, which has a theological meaning. The shell recalls a legend attributed to St Augustine, who met a child on the beach who was trying to scoop up the sea into a hole in the sand. Augustine asked him what he was doing. The child explained his vain attempt and Augustine took it to refer to his own futile endeavour to encompass the infinity of God within the confines of the limited human mind. The shell is also a symbol of pilgrims. His ordination as a Bishop has the symbol of the brown bear with a pack-saddle on its back. An ancient tradition tells that the first Bishop of Freising, St Corbinian (680-730), set out for Rome on horseback. While riding through a forest he was attacked by a bear that tore his horse to pieces. Corbinian not only managed to tame the animal but also to make it carry his baggage to Rome. A simple interpretation of the story would be that the bear tamed by God's grace is the Bishop of Freising himself, and the pack saddle is the burden of his Episcopate. His being named a Cardinal has the symbol next to it of the Moor's head, an ancient emblem of the Diocese of Munich and Freising. In the celebratory stamp, which features the papal election, there are all three symbols found in Benedict XVI's papal coat of arms.