These external causes of Russia’s aloofness were still more intensified by a systematic determination of Russia to keep out the Catholic contamination that would come from intercourse with Europe. This was a direct outgrowth of its adoption of Christianity from Byzantium, instead of Rome. Cyril and Methodius, the apostles to the Slavs, were themselves Bulgarians from Macedonia. When they first carried the new religion to Moravia and later to Bulgaria, they, no doubt, preached and wrote in the dialect with which they were most familiar. This innovation of preaching the gospel in another than one of the three sacred languages was a necessary departure, in order to win over the troublesome Slavs to the north of Byzantium. Though at the end of the ninth century the various dialects were already sufficiently dissimilar to constitute separate languages, yet they were not so distant from each other as to be a hindrance to a free intercommunication. When, a century later, Christianity was introduced into Russia from Constantinople, Bulgarian priests and bookmen were the natural intermediaries, and the Bulgarian language at once became the literary medium, to the exclusion of the native tongue. Soon after, the Eastern Church separated from Rome, and the Greek-Catholic clergy inculcated upon their neophytes an undying hatred of the Latins, as the Romanists were called. In Moscow, the slightest deviation from the orthodox faith was sufficient cause for suspecting a Romanist heresy, and anathemas against Roman-Catholics were frequent, but at Kíev, where the contact with Poland was inevitable, the disputes with the Latins form a prominent part of ecclesiastical literature. To guard the country against any possible contagion, the punishment of Russians who crossed the border, in order to visit foreign parts, was so severe, that few ever ventured out of the country. The seclusion of Russia was complete.