ocean, where tides and shoals formed a current
twenty miles across. It was the sight or the fancy of this furious surge
which frightened Henry's crews, for it plainly forbade all coasting and
compelled the seamen to strike into the open sea out of sight of land.
And though the discovery of Porto Santo had proved the feasibility and
the gain of venturing boldly into the Sea of Darkness, and though since
that time (1418) the Prince had sent out his captains due west to the
Azores and south-west to Madeira, both hundreds of miles from the
continent, yet in rounding Bojador there were not only the real terrors
of the Atlantic, but the legends of the tropics to frighten back the
boldest.

Most mariners had heard it said that any Christian who passed Bojador
would infallibly be changed into a black, and would carry to his end
this mark of God's vengeance on his insolent prying. The Arab tradition
of the Green Sea of Night had too strongly taken hold of Christian
thought to be easily shaken off. And it was beyond the Cape which
bounded their knowledge that the Saracen geographers had fringed the
coast of Africa with sea-monsters and serpent rocks and water unicorns,
instead of place names, and had drawn the horrible giant hand of Satan
raised above the waves to seize the first of his human prey that would
venture into his den. If God made the firm earth, the Devil made the
unknown and treacherous ocean--this was the real lesson of most of the
mediaeval maps, and it was this ingrained superstition that Henry found
his worst enemy, appearing as it did sometimes even in his most trusted
and daring captains.

And then again, the legends of Tropical Africa, of the mainland beyond
Bojador, were hardly less terrible than those of the Tropical Ocean. The
Dark Continent, with its surrounding Sea of Darkness, was the home of
mystery and legend. We have seen how ready the Arabs were to write
Uninhabitable over any unknown country--dark seas and lands were simply
those that were dark to them, like the Dark Ages to others, but nowhere
did their imagination revel in genies and fairies and magicians and all
the horrors of hell, with more enthusiastic and genial interest than in
Africa. Here only the northern parts could be lived in by man. In the
south and central deserts, as we have heard from the Moslem doctors
themselves, the sun poured down sheets of liquid flame upon the ground
and kept the sea and the rivers boiling day and night wit