One need only mention works which are still widely read and which have influenced our own civilization—Plutarch’s Lives, Marcus Aurelius’ Meditations, and the New Testament. They are all written in Greek, and who will venture to assert that the age in which they were written falls outside Greek history, or that the social experience which produced them was not an act in the tragedy of Hellenic civilization?
Even statistically the Empire was more Greek than anything else. Probably a considerable majority of its inhabitants spoke Greek as a lingua franca, if not as their mother-tongue. Nearly all the great industrial and commercial centres were in the Greek or Hellenized provinces. Possibly, during the first two centuries of the Empire, more Greek was spoken than Latin by the proletariat of Rome itself.
The Greek core of the Roman Empire played the part of Western Europe in the modern world. The Latinized provinces were thinly populated, backward, and only superficially initiated into the fraternity of civilization. The pulse of the Empire was driven by a Greek heart, and it beat comparatively feebly in the non-Greek extremities.
From Arnold Toynbee: Ancient Greek History and the West
Cf. Greek Orthodoxy – From Apostolic Times to the Present Day
Page 12
