but at any rate by the time of Saint Ambrose it had become extremely impressive. The power and
the separateness of the priesthood were taken from the East, but were gradually strengthened by
methods of government, in the Church, which owed much to the practice of the Roman Empire.
The Old Testament, the mystery religions, Greek philosophy, and Roman methods of
administration were all blended in the Catholic Church, and combined to give it a strength which
no earlier social organization had equalled.
The Western Church, like ancient Rome, developed, though more slowly, from a republic into a
monarchy. We have seen the stages in the growth of papal power, from Gregory the Great through
Nicholas I, Gregory VII, and Innocent III, to the final defeat of the Hohenstaufen in the wars of
Guelfs and Ghibellines. At the same time Christian philosophy, which had hitherto been
Augustinian and therefore largely Platonic, was enriched by new elements due to contact with
Constantinople and the Mohammedans. Aristotle, during the thirteenth century, came to be known
fairly completely in the West, and, by the influence of Albertus Magnus and Thomas Aquinas,
was established in the minds of the learned as the supreme authority after Scripture and the
Church. Down to the present day, he has retained this position among Catholic philosophers. I
cannot but think that the substitution of Aristotle for Plato and Saint Augustine was a mistake
from the Christian point of view. Plato's temperament was more religious than Aristotle's, and
Christian theology had been, from almost the first, adapted to Platonism. Plato had taught that
knowledge is not perception, but a kind of reminiscent vision; Aristotle was much more of an
empiricist. Saint Thomas, little though he intended it, prepared the way for the return from
Platonic dreaming to scientific observation.
Outward events had more to do than philosophy with the disintegration of the Catholic synthesis
which began in the fourteenth century. The Byzantine Empire was conquered by the Latins in
1204, and remained in their hands till 1261. During this time the religion of its government was
Catholic, not Greek; but after 1261 Constantinople was lost to the Pope and never recovered, in
spite of nominal union at Ferrara in 1438. The defeat of the Western Empire in its conflict with
the papacy proved useless to the Church, owing to the rise of national monarchies in France and
England; throughout most