On this stage, then, we find the Semitic and the Indo-Germanic races transferring to each other the characteristics with which they were most happily endowed by nature. The mosque schools of the Arabians were conducted on the model of the Alexandrian schools. The old Egyptian and Jewish colleges were to some extent the prototypes of these, and some writers think that our own universities were suggested by those of the Saracens. How great and famous some of these must have been, may be learned from the fact that, as we have stated, no less than six thousand professors and students were collected together at Baghdad at one time. There were lecture rooms, laboratories, hospitals, and residences for teachers and students, besides the great halls which must have been required for the vast libraries which the Caliphs collected. It was in Spain perhaps that Saracenic learning shone most brilliantly. In the early part of the eighth century was founded the noble university of Cordova, the city which, under Arabian rule, was called the “Centre of Religion, the Mother of Philosophers, the Light of Andalusia.” It contained 300 mosques, 200,000 houses, and 1,000,000 inhabitants, besides forty hospitals.[703] Abou-Ryan-el-Byrouny (died 941) travelled forty years studying mineralogy, and his treatise on precious stones, says Sismondi,[704] is a rich collection of facts. Aben-al-Beïthar of Malaga travelled over all the mountains and plains of Europe in search of plants, and rendered most important services to botany. He wandered over the sands of Africa and the remotest countries of Asia, examining and collecting animals, fossils, and vegetables, and published his observations in three volumes, which contained more science than any naturalist had previously recorded.[705] In one sense the Arabians were the inventors of chemistry, and never was the science applied to the arts of life more beneficially than by the Saracens in Spain. Mahomet was skilled in the knowledge of medicine, and certain of his aphorisms are extant concerning the healing art. Gibbon says[706] that the temperance and exercise his followers preached, deprived the doctors of the greater part of their practice. The only medicine recommended by the Koran is honey (see Surah xvi. 71). “From its (the bee’s) belly cometh forth a fluid of varying hues, which yieldeth medicine to man.” There is evidence of a belief in magic in the Koran as a charm against evil, and of incantations capable of producing ill consequences to those against whom they were directed. The 113th chapter of the Koran was written when Mohammed believed that, by the witchcraft of wicked persons, he had been afflicted with rheumatism. Mohammedan peoples use as amulets to avert evil from themselves or possessions, a small Koran encased in silk or leather, or some of the names of God, or of the prophets or saints, or the Mohammedan creed engraven on stone or silver.