John had no liking for religious controversies within his own Church, and although Cantacuzenus in his retirement wished that the most important of them should be continued John forbade it. There was a curious theological controversy, related by the writers of the time, which is of value as showing that in the midst of the most grave political difficulties the Byzantine people had not yet lost their interest in religious questions. Barlaam, a Calabrian abbot of the Greek Church--who, as we have seen, had been sent to Rome to negotiate for Union and aid because, among other reasons, he was well acquainted with Latin, ‘better indeed than with Greek’[76]--charged certain monks at Mount Athos and their followers, known as Bogomils, with heresy, called them Omphalopsychae, Messalians, men who believed that by looking long at their navel they could see God with mortal eyes,[77] or at least with the uncreated light of Mount Tabor. Barlaam’s great opponent was Palamas, archbishop of Salonica. The party headed by Palamas was favoured by Cantacuzenus, whose mother, indeed, was a Bogomil. The controversy waxed fierce and bitter, but Barlaam was unable to obtain the condemnation he desired. It raged for fifteen years until forcibly put an end to by John on the withdrawal of his colleague.[78] By far the most important difficulty which John had to face was the constantly increasing encroachments by the Turks. Their influence at the beginning of his sole occupancy of the throne is shown by the consent he was forced to give to the engagement of his infant daughter to the son of Orchan, the great Turkish leader and successor of Othman. Their influence at a later period, in 1374, is shown by his having been forced into an alliance with Murad and, towards the end of his reign, by his having to destroy a part of the walls of the capital at Murad’s bidding.