In the first place, [it] is visible to us in perspective and can be seen by us as a whole, because it is over – in contrast to the history of our own Western world, which is a still-unfinished play of which we do not know the eventual ending and cannot even see the present general aspect from our own position as momentary actors on its crowded and agitated stage.
In the second place, the field of Graeco-Roman history is not encumbered and obscured by a surfeit of information, and so we can see the wood – thanks to a drastic thinning of the trees during the interregnum between the dissolution of the Graeco-Roman society and the emergence of our own. Moreover, the conveniently manageable amount of evidence that has survived is not overweighted by the state papers of parochial principalities, like those which, in our Western world, have accumulated, ton upon ton […]. The surviving materials for a study of Graeco-Roman history are not only manageable in quantity and select in quality; they are also well-balanced in their character. Statues, poems, and works of philosophy count here for more than the texts of laws and treaties; and this breeds a sense of proportion in the mind of a historian […]; for – as we can see in the perspective given by lapse of time more easily than we can see it in the life of our own generation – the works of artists and men of letters outlive the deeds of business men, soldiers, and statesmen. The poets and the philosophers outrange the historians; while the prophets and the saints overtop and outlast them all. The ghosts of Agamemnon and Pericles haunt the living world of to-day by grace of the magic words of Homer and Thucydides; and, when Homer and Thucydides are no longer read, it is safe to prophesy that Christ and the Buddha and Socrates will still be fresh in the memory of (to us) almost inconceivably distant generations of men.
The third, and perhaps greatest, merit of Graeco-Roman history is that its outlook is oecumenical rather than parochial. Athens may have eclipsed Sparta and Rome Samnium, yet Athens in her youth made herself the education of all Hellas, while Rome in her old age made the whole Graeco-Roman world into a single commonwealth. In Graeco-Roman history, surveyed from beginning to end, unity is the dominant note; and, when once I had heard this great symphony, I was no longer in danger of being hypnotized by the lone and outlandish music of the parochial history of my own country, which had once enthralled me when I listened to my mother telling it to me in instalments, night by night, as she put me to bed. The historical pastors and masters of my mother’s generation, not only in England but in all Western countries, had been eagerly promoting the study of national history in the mistaken belief that it had a closer bearing on their countrymen’s lives and was, therefore, somehow more readily accessible to their understanding than the history of other places and times (although it is surely evident that, in reality, Jesus’ Palestine and Plato’s Greece were more potently operative than Alfred’s or Elizabeth’s England in the lives of English men and women of the Victorian age).
Civilization on Trial, OUP, 1948