With the advent of the Dark Ages the movement of course ceased, and it did not begin anew for many centuries; while a thousand years passed before it was once more in full swing, so far as European civilization, so far as the world civilization of to-day, is concerned.  During all those centuries the civilized world, in our acceptation of the term, was occupied, as its chief task, in slowly climbing back to the position from which it had fallen after the age of the Antonines.  Of course a general statement like this must be accepted with qualifications.  There is no hard and fast line between one age or period and another, and in no age is either progress or retrogression universal in all things.  There were many points in which the Middle Ages, because of the simple fact that they were Christian, surpassed the brilliant pagan civilization of the past; and there are some points in which the civilization that succeeded them has sunk below the level of the ages which saw such mighty masterpieces of poetry, of architecture—­especially cathedral architecture—­and of serene spiritual and forceful lay leadership.  But they were centuries of violence, rapine, and cruel injustice; and truth was so little heeded that the noble and daring spirits who sought it, especially in its scientific form, did so in deadly peril of the fagot and the halter.

During this period there were several very important extra-European movements, one or two of which deeply affected Europe.  Islam arose, and conquered far and wide, uniting fundamentally different races into a brotherhood of feeling which Christianity has never been able to rival, and at the time of the Crusades profoundly influencing European culture.  It produced a civilization of its own, brilliant and here and there useful, but hopelessly limited when compared with the civilization of which we ourselves are the heirs.  The great cultured peoples of southeastern and eastern Asia continued their checkered development totally unaffected by, and without knowledge of, any European influence.

Throughout the whole period there came against Europe, out of the unknown wastes of central Asia, an endless succession of strange and terrible conqueror races whose mission was mere destruction—­Hun and Avar, Mongol, Tartar, and Turk.  These fierce and squalid tribes of warrior horsemen flailed mankind with red scourges, wasted and destroyed, and then vanished from the ground they had overrun.  But in no way worth noting did they count in the advance of mankind.

At last, a little over four hundred years ago, the movement towards a world civilization took up its interrupted march.  The beginning of the modern movement may roughly be taken as synchronizing with the discovery of printing, and with that series of bold sea ventures which culminated in the discovery of America; and after these two epochal feats had begun to produce their full effects in material and intellectual life, it became inevitable that civilization