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 Church, which supported the ruling classes of the
country and lent them authority at the same time that it increased its
own, was antipathetic to the Slavs, and the Bogomil heresy drew much
strength from its nationalistic colouring and from the appeal which it
made to the character of the Balkan Slavs, who have always been intolerant
of government by the Church. But neither the civil nor the ecclesiastical
authorities were able to cope with the problem; indeed they were apt to
minimize its importance, and the heresy was never eradicated till the
arrival on the scene of Islam, which proved as attractive to the
schismatics as the well-regulated Orthodox Church had been the reverse.

The third quarter of the tenth century witnessed a great recrudescence of
the power of Constantinople under the Emperor Nikiphóros Phokas, who
wrested Cyprus and Crete from the Arabs and inaugurated an era of
prosperity for the eastern empire, giving it a new lease of vigorous and
combative life. Wishing to reassert the Greek supremacy in the Balkan
peninsula his first act was to refuse any further payment of tribute to
the Bulgarians as from 966; his next was to initiate a campaign against
them, but in order to make his own success in this enterprise less costly
and more assured he secured the co-operation of the Russians under
Svyatoslav, Prince of Kiev; this potentate's mother Olga had visited
Constantinople in 957 and been baptized (though her son and the bulk of
the population were still ardent heathens), and commercial intercourse