Benedict XVI made the remarks during the illustration of the figure of St Leo the Great, to whom he dedicated today`s address for the general audience, to again assert the purpose of Petrine primacy and to recall its existence since the time of the undivided Church. The affirmation comes on the eve of a visit from ecumenical patriarch Bartholomew I to the Vatican, and shortly after the Catholic-Orthodox meeting in Ravenna, which acknowledged the principle of the primacy of the bishop of Rome, leaving open the question of its concrete exercise in relation to the role of the synod. At today`s general audience, which was again divided into two segments because of the great number of the faithful who were split between the basilica of Saint Peter and the Paul VI hall, the pope continued his reflection on the Fathers of the Church, speaking of St. Leo the Great, "one of the greatest pontiffs ever to have honoured the Roman see", "the first pope whose preaching has come down to our time". His pontificate began in 440, "undoubtedly one of the most important [pontificates] in the history of the Church", in "very difficult" times. The repeated assaults of the barbarian invasions, the weakening of the authority of the empire, and a grave social crisis, in the words of the pope, "had forced" the bishop of Rome to take on a role in the civil sphere as well, which increased the prestige of the Roman see. Benedict XVI recalled the best-known episode in the life of Leo the Great, when in 452 he went to Mantua and convinced Attila, leader of the Huns, not to continue with his invasion. "It was a memorable sign of the peacemaking activity conducted by the pontiff". But he did not have similar success with his attempt, in the spring of 455, to prevent the invasion and sacking of Rome on the part of the Vandals. "The gesture of the pope, who went unarmed to meet the invader, at least prevented Rome from being burned" and allowed the basilicas of St Peter, St Paul, and St John to be spared, "in which part of the terrorised population took refuge". He was "a theologian and pastor, at the service of communion and a tireless promoter of Roman primacy, showing himself an authentic heir of the apostle Peter, and the Eastern bishops also showed in their awareness of this". So it was in 451, when the Council of Chalcedon addressed the "Christological controversy", affirming the union in the one person of Christ, without confusion and without separation, of his two natures as true God and true man. The principle was affirmed by Leo in an important doctrinal text that was read at Chalcedon and "welcomed with significant acclamation". The primacy of the pope is, therefore, a "primacy of communion", "at the service of truth and charity" and "also at the service of communion among the different Churches". Citing Leo, the pope finally repeated: "what was communicated to all the apostles was entrusted to only one of them".