from the third century before Christ to the third century after was a
period of extraordinary intellectual expansion and moral awakening; but
when we observe the governmental changes introduced under the emperor
Diocletian at the very end of this period, we realize how serious had
been the political retrogression, how grave the danger that the stream
of human life might come to stagnate in Europe, as it had long since
stagnated in Asia.

Two mighty agents, cooperating in their opposite ways to prevent any
such disaster, were already entering upon the scene. The first was the
colonization of the empire by Germanic tribes already far advanced
beyond savagery, already somewhat tinctured with Roman civilization, yet
at the same time endowed with an intense spirit of personal and local
independence. With this wholesome spirit they were about to refresh and
revivify the empire, but at the risk of undoing its work of political
organization and reducing it to barbarism. The second was the
establishment of the Roman church, an institution capable of holding
European society together in spite of a political disintegration that
was widespread and long-continued. While wave after wave of Germanic
colonization poured over romanized Europe, breaking down old
boundary-lines and working sudden and astonishing changes on the map,
setting up in every quarter baronies, dukedoms, and kingdoms fermenting
with vigorous political life; while for twenty generations this salutary
but wild and dangerous work was going on, there was never a moment when
the imperial sway of Rome was quite set aside and forgotten, there was
never a time when union of some sort was not maintained through the
dominion which the church had established over the European mind. When
we duly consider this great fact in its relations to what went before
and what came after, it is hard to find words fit to express the debt of
gratitude which modern civilization owes to the Roman Catholic church.