But there are certain features in the medieval theory of which we must not ignore the significance.  In the first place, while it maintained the belief in degeneration, endorsed by Hebrew mythology, it definitely abandoned the Greek theory of cycles.  The history of the earth was recognised as a unique phenomenon in time; it would never occur again or anything resembling it.  More important than all is the fact that Christian theology constructed a synthesis which for the first time attempted to give a definite meaning to the whole course of human events, a synthesis which represents the past as leading up to a definite and desirable goal in the future.  Once this belief had been generally adopted and prevailed for centuries men might discard it along with the doctrine of Providence on which it rested, but they could not be content to return again to such views as satisfied the ancients, for whom human history, apprehended as a whole, was a tale of little meaning. [Footnote:  It may be observed that Augustine (De Civ.  Dei, x. 14) compares the teaching (recta eruditio) of the people of God, in the gradual process of history, to the education of an individual.  Prudentius has a similar comparison for a different purpose (c.  Symmachum, ii. 315 sqq.): 

Tardis semper processibus aucta Crescit vita hominis et longo proficit usu.  Sic aevi mortalis habet se mobilis ordo, Sic variat natura vices, infantia repit, etc.

Floras (Epitome, ad init.) had already divided Roman history into four periods corresponding to infancy, adolescence, manhood, and old age.]

They must seek for some new synthesis to replace it.

Another feature of the medieval theory, pertinent to our inquiry, was an idea which Christianity took over from Greek and Roman thinkers.  In the later period of Greek history, which began with the conquests of Alexander the Great, there had emerged the conception of the whole inhabited world as a unity and totality, the idea of the whole human race as one.  We may conveniently call it the ecumenical idea—­the principle of the ecumene or inhabited world, as opposed to the principle of the polis or city.  Promoted by the vast extension of the geographical limits of the Greek world resulting from Alexander’s conquests, and by his policy of breaking down the barriers between Greek and barbarian, the idea was reflected in the Stoic doctrine that all men are brothers, and that a man’s true country is not his own particular city, but the ecumene. [Footnote:  Plutarch long ago saw the connection between the policy of Alexander and the cosmopolitan teaching of Zeno.  De Alexandri Magni virtute, i.  Sec. 6.] It soon became familiar, popularised by the most popular of the later philosophies of Greece; and just as it had been implied in the imperial aspiration and polity of Alexander, so it was implied, still more clearly, in the imperial theory of Rome.  The idea of the Roman Empire, its theoretical justification, might be described as the realisation