became almost universal, for, as the episcopal office could not be conferred upon men who were married, it developed, in a way, into a privilege of the religious who had taken the vow of celibacy. Owing to this the monks formed a class apart, corresponding to the upper clergy of the Western Churches; this gave and still gives a preponderating influence to the monasteries themselves. In some of them theological instruction is given both to clerics and to laymen. In the East the convents for women adopted the Rule of St. Basil and had constitutions copied from those of the Basilian monks. St. Cyril and St. Methodius, the Apostles of the Slavs were noted missionaries. In 1980, Pope John Paul II declared them co-patron saints of Europe, together with Benedict of Nursia. During the Muslim conquest, a large number of monasteries were destroyed, especially those monasteries in Anatolia and the region around Constantinople. Basilians in Italy After the Great Schism most Basilian monasteries became a part of the Eastern Orthodox Church; however, some Basilian monasteries which were in Italy remained in communion with the Western Church. St. Nilus the Younger was a monk and a propagator of the rule of Saint Basil in Italy. The Oratory of Saint Mark in Rossano, was founded by Nilus, as a place of retirement for nearby eremite monks. It retained the Greek Rite over the Latin Rite long after the town came under Norman rule. The Rossano Gospels is a 6th-century illuminated manuscript Gospel Book written following the reconquest of the Italian peninsula by the Byzantine Empire. In 1004, Nilus founded the Basilian Monastery of Santa Maria, in Grottaferrata; it was completed by his disciple Bartholomew of Grottaferrata, who was also of Greek heritage. The emigration of the Greeks to the West after the fall of Constantinople gave a certain prestige to these communities. Cardinal Bessarion, who was Abbot of Grottaferrata, sought to stimulate the intellectual life of the Basilians by means of the literary treasures which their libraries contained. Other Italian monasteries of the Basilian Order were affiliated with the monastery of Grottaferrata in 1561. The Spanish Basilians were suppressed with the other orders in 1835 and have not been re-established. Religious orders Order of Saint Basil the Great: a Ukrainian/Belarusian monastic religious order of the Greek Catholic Churches founded in 1631, and which has its Mother House in Rome at Santi Sergio