there; Leo learned of it around 443, and proceeded against them by holding a public debate with their representatives, burning their books and writing letters of warning to the Italian bishops. His attitude was as decided against the Priscillianists. Bishop Turibius of Astorga, astonished at the spread of the sect in Spain, had addressed the other Spanish bishops on the subject, sending a copy of his letter to Leo, who took the opportunity to write an extended treatise (21 July 447) against the sect, examining its false teaching in detail and calling for a Spanish general council to investigate whether it had any adherents in the episcopate. From a pastoral perspective, he galvanized charitable works in a Rome beset by famines, an influx of refugees, and poverty. He further associated the practice of fasting with charity and almsgiving particularly on the occasion of the Quattro tempora, (the quarterly Ember days). It was during Leo's papacy that the term "Pope", which previously meant any bishop, came to exclusively mean the Bishop of Rome. Papal authority Leo drew many learned men about him and chose Prosper of Aquitaine to act in some secretarial or notarial capacity. Leo was a significant contributor to the centralisation of spiritual authority within the Church and in reaffirming papal authority. In 450, the Byzantine Emperor Theodosius II, in a letter to Pope Leo I, was the first to call the Bishop of Rome the Patriarch of the West, a title that would continue to be used by the popes up until as recently as 2006. Various regional matters On several occasions, Leo was asked to arbitrate disputes in Gaul. Patroclus of Arles (d. 426) had received from Pope Zosimus the recognition of a subordinate primacy over the Gallican Church which was strongly asserted by his successor Hilary of Arles. An appeal from Chelidonius of Besançon gave Leo the opportunity to assert the pope's authority over Hilary, who defended himself stoutly at Rome, refusing to recognize Leo's judicial status. Feeling that the primatial rights of the bishop of Rome were threatened, Leo appealed to the civil power for support and obtained, from Valentinian III, a decree of 6 June 445, which recognized the primacy of the bishop of Rome based on the merits of Peter, the dignity of the city, and the legislation of the First Council of Nicaea; and provided for the forcible extradition by provincial governors