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