Persia went down before them. By 640 they had trampled Egypt under foot,
and destroyed the celebrated Alexandrian library.[11] They swept over
all Africa, completely obliterating every trace of Vandal or of Roman.
Their dominion reached farther east than that of Alexander. They wrested
most of its Asiatic possessions from the pretentious Empire at
Constantinople, and reduced that exhausted State to a condition of
weakness from which it never arose. Then, passing on through their
African possessions, they entered Spain and overthrew the kingdom of
the Visigoths.[12] It was a storm whose end no man could measure, whose
coming none could have foreseen. And then, just a century after
Mahomet's death, the Arabs, pressing on through Spain, encountered the
Franks on the plains of France.

A thousand years had passed since Semitic Carthage had fallen before
Aryan Rome. Now once again the Semites, far more dangerous because in
the full tide of the religious frenzy of their race, threatened to
engulf the Aryan world. They were repulsed by the still sturdy Franks
under their great leader, Charles Martel, at Tours. The battle of
Tours[13] was only less momentous to the human race than that of
Chalons. What the Arab domination of Europe would have meant we can
partly guess by looking at the lax and lawless states of Northern Africa
to-day. These fair lands, under both Roman and Vandal, had long been
sharing the lot of Aryan Europe; they seemed destined to follow in its
growth and fortune. But the Arab conquest restored them to Semitism,
made Asia the seat from which they were to have their training, attached
them to the chariot of sloth instead of that of effort. What they are
to-day, all Europe might have been.

Yet with the picture of these fifth and sixth and seventh centuries of
battle full before us, we are not tempted to glory overmuch even in such
victories as Tours and Chalons. We see war for what it has ever
been--the curse of man, the hugest hinderance to our civilization. While
men fight they have small time for thought or art or any soft or kindly
sentiment. The survivors may with good luck develop into a stronger
breed; they are inevitably more brutal.

We thus begin to recognize just how necessary for human progress was the
work Rome had been engaged in. By holding the world at peace, she had
given humankind at least the opportunity to grow. The moment her
restraining hand was shaken off, war sprang up everywhere.