Simeon died in 927, and his son Peter, who succeeded him, was a lover of peace and comfort; he married a Byzantine princess, and during his reign (927-69) Greek influence grew ever stronger, in spite of several revolts on the part of the Bulgar nobles, while the capital Preslav became a miniature Constantinople.  In 927 Rome recognized the kingdom and patriarchate of Bulgaria, and Peter was duly crowned by the Papal legate.  This was viewed with disfavour by the Greeks, and they still called Peter only arch[=o]n or prince (knyaz in Bulgarian), which was the utmost title allowed to any foreign sovereign.  It was not until 945 that they recognized Peter as basileus, the unique title possessed by their own emperors and till then never granted to any one else.  Peter’s reign was one of misfortune for his country both at home and abroad.  In 931 the Serbs broke loose under their leader [)C]aslav, whom Simeon had captured but who effected his escape, and asserted their independence.  In 963 a formidable revolt under one Shishman undermined the whole state fabric.  He managed to subtract Macedonia and all western Bulgaria, including Sofia and Vidin, from Peter’s rule, and proclaimed himself independent tsar (tsar or caesar was a title often accorded by Byzantium to relatives of the emperor or to distinguished men of Greek or other nationality, and though it was originally the equivalent of the highest title, it had long since ceased to be so:  the emperor’s designations were basileus and autocrat[=o]r).  From this time there were two Bulgarias—­eastern and western.  The eastern half was now little more than a Byzantine province, and the western became the centre of national life and the focus of national aspirations.

Another factor which militated against the internal progress of Bulgaria was the spread of the Bogomil heresy in the tenth century.  This remarkable doctrine, founded on the dualism of the Paulicians, who had become an important political force in the eastern empire, was preached in the Balkan peninsula by one Jeremiah Bogomil, for the rest a man of uncertain identity, who made Philippopolis the centre of his activity.  Its principal features were of a negative character, and consequently it was very difficult successfully to apply force against them.  The Bogomils recognized the authority neither of Church nor of State; the validity neither of oaths nor of human laws.  They refused to pay taxes, to fight, or to obey; they sanctioned theft, but looked upon any kind of punishment as unjustifiable; they discountenanced marriage and were strict vegetarians.  Naturally a heresy so alarming in its individualism shook to its foundations the not very firmly established Bulgarian society.  Nevertheless it spread with rapidity in spite of all persecutions, and its popularity amongst the Bulgarians, and indeed amongst all the Slavs of the peninsula, is without doubt partly explained by political reasons.  The hierarchy of the Greek