symbol of
faith. Thus arose the celebrated controversy on the "Filioque," which
was one of the chief causes of the great schism between the Eastern and
Western Churches in the ninth century.

The Arian, Manichaean, Marcionite, and Monothelite heresies spread,
during this century, through the Greek Church, and, where the Arabians
ruled, the Nestorians and Monophysites also flourished. In the Latin
Church a phase of the Nestorian heresy made its way, under the name of
Adoptianism, a name given because its adherents regarded Christ, so far
as his manhood was concerned, as the Son of God by adoption only.

CENTURY IX.

Christendom, during this century, as during the preceding one, was
threatened and harassed by the inroads of Mahommedan powers, and the
first gleams of returning light began to penetrate its thick
darkness--light proceeding from the Arabians and the Saracens, the
restorers of knowledge and of science. It is not here our duty to trace
that marvellous work of the revival of thought--thought which
Christianity had slain, but which, revived by Mahommedanism, was
destined to issue in the new birth of heretic philosophy. While this
work was proceeding among the Saracens, the Arabians, and the Moors,
Christendom went on its way, degraded, vicious, and superstitious; only
here and there an effort at learning was made, and some few went to the
Arabian schools, and returned with some tincture of knowledge. John
Scotus Erigena, a subtle and acute thinker, left behind him works which
have made some regard him as the founder of the _Realist_ school of the
middle ages, the school which followed Aristotle, in opposition to the
_Nominalists_, who held with Zeno and the Stoics. Erigena taught that
the soul would be re-absorbed into the divine spirit, from which it had
originally emanated; from God all things had come--to Him would they
ultimately return; God alone was eternal, and in the end nothing but God
would exist. Some of Erigena's works naturally fell under the
displeasure of the Church, and were duly burned: he was a philosopher,
and therefore dangerous.

While this slight effort at thought was thus frowned upon, vice made its
way unchecked and unrebuked by the authorities. "The impiety and
licentiousness of the greater part of the clergy arose, at this time, to
an enormous height, and stand upon record in the unanimous complaints of
the most candid and impartial writers of this century. In the East,
tumult,