The Arabians had a corrupt form of idolatry which came from the Persians, and worshipped not one, but a great many gods.
Mahomet sincerely believed that he was inspired by the one true and great God to overthrow this old religion and to establish a pure and true one.
Under this inspiration he wrote the Koran, which is the Mahometan Bible. This book told them of the sins they must not commit, and of the joys which hereafter awaited those who should be faithful to the teachings of the one God and his prophet Mahomet.
The fatal element in this religion was its cruelty. The Prophet had declared that it should be enforced with the sword, that it should be: the Koran--or death!
It spread with the fury of a conflagration. The Arabs, or Saracens, as they were called, conquered Persia and Syria and Egypt. After that they began to look enviously at Constantinople and to dream of universal empire like the Romans. They were not a horde of ignorant barbarians like the Goths. They came from an ancient seat of learning, and their leaders were men of knowledge and attainments far beyond anything existing in Europe at that time.
In the year 710, like a flock of vultures a great Mahometan host swooped down upon Christian Europe.
Spain was the extreme western limit of the Roman Empire. It was the plan of these terrible Saracens, after conquering Spain, to sweep over the Pyrenees into France. Then another Saracen army, after conquering Constantinople, was to flow westward, and the two streams would meet at Rome.
It was a very nice plan--for the Saracens! But they did _not_ get over the Pyrenees. Nor did they take Constantinople until six hundred years later. So they were content to establish themselves firmly in Spain and upon the African coast opposite, and bided their time.
After the occupation of Northern Africa and Spain, they were no longer call Saracens, but Moors. They lingered in Spain until the discovery of America; and the final expulsion of the Moors from the Spanish peninsula, which was effected with great cruelty, took place during the reign of Ferdinand and Isabella. They made Spain beautiful, and they made it great.
When the Goths flowed in a rough torrent over Southern Europe they effaced civilization. But this Saracen wave of conquest bore on its crest--but only on its crest--art, refinements, and culture of a type unknown to Europe. The twilight of the Middle Ages was illumined by a revival of Greek culture at Constantinople, and by Saracenic art and erudition in Spain.