council--which condemned the use and worship of images. Leo IV. (A.D.
775) issued penal laws against image worshippers, but he was poisoned by
Irene, his wife, in A.D. 780, and she entered into an alliance with Pope
Adrian, so that the Iconoduli became triumphant in their turn. While
this controversy raged, a second arose as to the procession of the Holy
Ghost. The creed of Constantinople (see ante, p. 434) ran--"I believe in
the Holy Ghost, the Lord and Giver of Life, who proceedeth from the
Father;" to this phrase the words, "and the Son," had been added in the
West, originally by some Spanish bishops; the Greeks protested against
an unauthorised addition being inserted into a creed promulgated by a
general council, and received by the universal Church as the 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, Manichæan, 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