Gregory's policy was to uphold and extend the Petrine theory to the utmost, although personally refusing the title of "Universal Bishop." He censured the ambitious Patriarch of Constantinople for assuming that title and wrote to John of Syracuse: "With regard to the church of Constantinople, who doubts that it is subject to the Apostolic See? . . . The Apostolic See is the head of all churches."[189:1] To the Patriarch of Alexandria he wrote: "In the preface of the epistle . . . you have thought fit to make use of a proud title, calling me Universal Pope. But I beg your most sweet Holiness to do this no more."[189:2] Again he exclaimed: "Whoever calls himself Universal Bishop is Antichrist."[189:3] Gregory meant to exercise as much autonomy as possible in ruling the West but, at the same time, to submit to imperial authority in all instances of conflicting claims.[189:4] He planned to unify and purify the Church and to extend Christianity over the known world. Under Gregory's able management papal power was consolidated and made supreme in Western Europe. He systematised papal theology, and perfected and beautified the Church liturgy until it took three hours to celebrate the mass.[189:5] He regulated the calendar of festivals. He checked heresies by driving Manichæism and Arianism out of Italy, Spain, and Gaul, and even advised the persecution of African Donatists (591). The Jews, however, were tolerated and efforts made to convert them. To get rid of simony he personally refused all presents and abolished all fees in his court. From priest to bishop he corrected the clergy and urged upon them celibacy.[190:1] He restored discipline throughout the Church and patronised all sorts of charity. He fought paganism fiercely by denouncing the Roman classics and even boasting of his own ignorance of them,[190:2] while at the same time he sent missionaries over most all of Western Europe. Monasticism, which he himself had adopted with all his heart, he encouraged and improved by restoring the early rigid discipline; by separating monks and clergy; by restricting admission to religious houses to persons above the age of eighteen years; by insisting on a probation of two years; by condemning deserters to life imprisonment; and by favouring the Benedictine Rule as the model. The papal court was reorganised, and clergy were substituted for boys and secular adults to attend the Pope. Even some efforts were made to check the European slave-trade.