The established Christian Church took the best energies of Hellenism into its service. The Greek intellectuals ceased to become lecturers and professors, to find a more human and practical career in the bishop’s office. The Nicene Creed, drafted by an ‘oecumenical’ conference of bishops under the auspices of Constantine himself,[1] was the last notable formulation of Ancient Greek philosophy. The cathedral of Aya Sophia, with which Justinian adorned Constantinople, was the last original creation of Ancient Greek art.[2] The same Justinian closed the University of Athens, which had educated the world for nine hundred years and more, since Plato founded his college in the Academy. Six recalcitrant professors went into exile for their spiritual freedom, but they found the devout Zoroastrianism of the Persian court as unsympathetic as the devout Christianity of the Roman. Their humiliating return and recantation broke the ‘Golden Chain’ of Hellenic thought for ever. Hellenism was thus expiring from its own inanition, when the inevitable avalanche overwhelmed it from without. In the seventh century A.D. there was another religious eruption in the Semitic world, this time in the heart of Arabia, where Hellenism had hardly penetrated, and under the impetus of Islam the Oriental burst his bounds again after a thousand years. Syria was reft away from the Empire, and Egypt, and North Africa as far as the Atlantic, and their political severance meant their cultural loss to Greek civilization. Between the Koran and Hellenism no fusion was possible. Christianity had taken Hellenism captive, but Islam gave it no quarter, and the priceless library of Alexandria is said to have been condemned by the caliph’s order to feed the furnaces of the public baths. [Footnote 1: A.D. 325.] [Footnote 2: Completed A.D. 538.] While Hellenism was thus cut short in the east, a mortal blow was struck at its heart from the north. The Teuton had raided and passed on, but the lands he had depopulated were now invaded by immigrants who had come to stay. As soon as the last Goth and Lombard had gone west of the Isonzo, the Slavs poured in from the north-eastern plains of Europe through the Moravian gap, crossed the Danube somewhere near the site of Vienna, and drifted down along the eastern face of the Alps upon the Adriatic littoral. Rebuffed by the sea-board, the Slavonic migration was next deflected east, and filtered through the Bosnian mountains, scattering the Latin-speaking provincials before it to left and right, until it debouched upon the broad basin of the river Morava. In this concentration-area it gathered momentum during the earlier part of the seventh century A.D., and then burst out with irresistible force in all directions, eastward across the Maritsa basin till it reached the Black Sea, and southward down the Vardar to the shores of the Aegean.