3 In the present document I wish to make particular reference to the Epistle Grande Munus, by which Pope Leo III intended to remind the Church and the world of the apostolic merits of both the Brothers-not only of Methodius, who, according to tradition, ended his days at Velehrad in Greater Moravia in the year 885, but also of Cyril, whom death separated from his brother in 869, when he was in Rome, the city which received and which still preserves his relics with profound veneration in the Basilica of Saint Clement. Recalling the holy lives and apostolic merits of the two Brothers from Salonika, Pope Leo XIII fixed their annual liturgical feast on 7 July. After the Second Vatican Council, as a result of the liturgical reform, the feast was transferred to 14 February, which from the historical point of view is the date of the heavenly birthday of Saint Cyril. At a distance of over a hundred years from Pope Leo's Epistle, the new circumstances in which it so happens that there falls the eleventh centenary of the death of Saint Methodius encourage us to give renewed expression to the Church's memory of this important anniversary. And a particular obligation to do so is felt by the first Pope called to the See of Peter from Poland, and thus from the midst of the Slav nations. The events of the last hundred years and especially of the last decades have helped to revive in the Church not only the religious memory of the two holy Brothers but also a historical and cultural interest in them. Their special charisms have become still better understood in the light of the situations and experiences of our own times. A contribution to this has been made by many events which belong, as true signs of the times, to the history of the twentieth century; the first of these is that great event which took place in the life of the Church: the Second Vatican Council. In the light of the magisterium and pastoral orientation of that Councils we can look in a new way-a more mature and profound way-at these two holy figures, now separated from us by eleven centuries. And we can read in their lives and apostolic activity the elements that the wisdom of divine Providence placed in them, so that they might be revealed with fresh fullness in our own age and might bear new fruits.
Source: Slavorum Apostoli (Vatican.va)