HERESIES, like civilization itself, are apt to spread Westward from the East. The Gnostic seęds were to flower most richly not in Armenia nor in Bulgaria but in the Westernmost country of the Balkan peninsula and in Latin countries more Western still. By the end of the twelfth century the greatest centres of Bogomil activity were in Bosnia, in Lombardy and in France.

Nevertheless the heresy remained strong in its original birthplace; and the Balkan peninsula was regarded, even by the Western heretics, as its home. During the twelfth century the churches of Constantinople and Bulgaria still ranked as the chief heretic congregations. It was there that Bogomil doctrine had been fully evolved. Bulgaria was Bogomil's country; and Constantinople was still the greatest city of the Christian world The career of Nicetas, self-styled bishop of the heretics of Constantinople, in France in 1167 shows the respect that Constantinople still commanded. But it is doubtful if there was in fact a strong heretical body resident there. The city was well policed and the Emperors dangerously interested in theology. If there had been much heresy there would have been heresy-hunts, and some record would almost certainly have survived.

With the political decline of Constantinople the prestige of its heretical church faded. The centre of gravity of the heresy was moving westward, while after the Fourth Crusade the city was in full decay. In 1230 the Bogomils still formed a flourishing congregation in die Capital, side by side with a small Latin heretical church which was introduced almost certainly after the Latin conquest of 1204.