We are not allowed to say that Hellenic civilization has turned into Western Christendom by a process of development involving the accentuation of some of its elements, the fading away of others, and the emergence of certain new elements within itself and the borrowing of others from external sources. The philosophical principle involved in saying that would be the principle that a civilization may develop into new forms while yet remaining itself, whereas Toynbee’s principle is that if a civilization changes it ceases to be itself and a new civilization comes into being.
This is not a constraint on historical events, but a constraint on how we speak about our abstract historical entities.
