of the South." So he built a rampart of iron across the pass by which
alone Touran joined Iran, and henceforth Turks and Tartars were kept
outside. Till the Arabs reached the Caucasus, they generally supposed
this to answer to Alexander's wall; when facts dispelled this theory,
the unknown Ural or Altai Mountains served instead; finally, as the
Moslems became masters of Central Asia, the Wall of China, beyond the
Gobi desert, alone satisfied the conditions of shadowy but historic
grandeur, beyond all practical danger of verification.

(4.) In striking contrast with the steady advance of Arabic exploration
and trade in the Eastern Sea is the Moslem horror of the Western Ocean
beyond Europe and Africa, the "Green Sea of Darkness" or the Atlantic.
And what we have to note is that they imparted much of this paralysing
cowardice to the Christian nations. Only the Northmen of Scandinavia,
living a life apart, and forced to make their way over the wild North
Sea, were untouched by this southern superstition, and ventured across
the ocean by the Färoes, Iceland, and Greenland, to the coast of
Labrador.

The doctors of the Koran indeed thought that a man mad enough to embark
for the unknown, even on a coasting voyage, should be deprived of civil
rights. Ibn Said goes further, and says no one has ever done this:
"whirlpools always destroy any adventurer." As late as the generation
immediately before Henry the Navigator, about A.D. 1390, another light
of Moslem science declared the Atlantic to be "boundless, so that ships
dare not venture out of sight of land, for even if the sailors knew the
direction of the winds, they would not know whither those winds would
carry them, and as there is no inhabited country beyond, they would run
a risk of being lost in mist, fog, and vapour. The limit of the West is
the Atlantic Ocean."