From Salonica, City of Ghosts: Christians, Muslims and Jews, 1430-1950, by Mark Mazower (Vintage, 2006), pp. 242-243:
TO THE OTTOMAN AUTHORITIES what had always mattered were religious rather than national or linguistic differences: Balkan Christians were either under the authority of the Patriarch in Constantinople or they were—more rarely—Catholic or Protestant. The Patriarchate shared the same outlook; it was indifferent to whether its flock spoke Greek, Vlach, Bulgarian or any other language or dialect. As for the illiterate Slav-speaking peasants tilling the fields, they rarely felt strongly about either Greece or Bulgaria and when asked which they were, many insisted on being known simply, as they had been for centuries, as “Christians.”
In Salonica itself, the growth of the Christian population had come from continual immigration over centuries from outlying villages, often as distant as the far side of the Pindos mountains, where many of the inhabitants spoke not Greek but Vlach (a Romance language akin to Romanian), Albanian or indeed various forms of Slavic. The city’s life, schools and priests gave these villagers, or their children, a new tongue, and turned them into Greeks. In fact many famous Greek figures of the past were really Vlachs by origin, including the savant Mosiodax, the revolutionary Rhigas Velestinlis, as well as the city’s first “Greek” printers, the Garbolas family, and the Manakis brothers, pioneers of Balkan cinema. “Twenty years ago there was nothing in Balkan politics so inevitable, so nearly axiomatic, as the connection of the Vlachs with the Greek cause,” wrote Brailsford in 1905. “They had no national consciousness and no national ambition … With some of them Hellenism was a passion and an enthusiasm. They believed themselves to be Greek. They baptized their children ‘Themistocles’ and ‘Penelope.’ They studied in Athens and they left their fortunes to Greek schools and Greek hospitals.” So many Vlachs settled in Salonica that in 1880 a Romanian paper claimed, to the fury of the Greek community, that there were no genuine Greeks there at all. Changing—or rather, acquiring—nationality was often simply a matter of upward mobility and a French consul once notoriously boasted that with a million pounds he could make Macedonians into Frenchmen.
Money affected nationality in other ways as well. In the Ottoman system, the Orthodox Church was not merely a focus of spiritual life; it was also a gatherer of taxes. Peasants in the countryside, just like wealthy magnates in Salonica itself, chafed at the power and corruption that accompanied these privileges. But while most bishops and the higher ecclesiastical hierarchy spoke Greek—the traditional language of the church and religious learning—and looked down on the use of Slavic, most Christian peasants around Salonica spoke Bulgarian—or if not Bulgarian then a Slavic tongue close to it. This started to matter to the peasants themselves once they identified Greek with the language not merely of holy scripture but of excessive taxation and corruption. In 1860, the Bishop of Cassandra’s extortions actually drove some villagers under his jurisdiction to threaten to convert to Catholicism—French priests from Salonica contacted the families concerned, promising them complete freedom of worship and a “Bishop of your own creed who will not take a single piastre from you.” Other villagers from near Kilkis demanded a bishop who would provide the liturgy in Old Church Slavonic and got one after they too started to declare themselves for Rome.
Yet what these peasants were talking was about shifting their religious not their national allegiance and it took decades for the discontent of the village tax-payer to be further transformed into nationalism. Greek continued to be the language of upward mobility through the nineteenth century. As for Bulgarian self-consciousness, this was slow to develop. Sir Henry Layard visited Salonica in 1842 to enquire into the movement which was alleged to be in progress amongst the Bulgarians but he did not find very much. “The Bulgarians, being of the Greek faith” he wrote later, “were then included by the Porte in classifying the Christian subjects of the Sultan, among the Greeks. It was not until many years afterwards that the Christians to the south of the Balkans speaking the Bulgarian language, were recognized as a distinct nation. At the time of my visit to Salonica no part of its Christian population, which was considerable, was known as Bulgarian.”
What led Slavic speakers to see their mother tongue in a new light was the influence of political ideologies coming from central and eastern Europe. German-inspired romantic nationalism glorified and ennobled the language of the peasantry and insisted it was as worthy of study and propagation as any other. Pan-Slavism—helped along perhaps by Russian agents—gave them pride in their unwritten family tongue and identified the enemy, for the first time, as Greek cultural arrogance. “I feel a great sorrow,” wrote Kiryak/Kyriakos Durzhiovich/Darlovitsi, the printer, “that although I am a Bulgarian I do not know how to write in the Bulgarian language.”