It has been frequently stated that the influence of the Peripatetic philosophy has been inimical to the development of science. But, in reality, the founder of that school, a descendant of Esculapius, and undoubtedly one of the greatest and most enlightened thinkers of antiquity, was an ideal man of science. This is abundantly evident from such of his works as can be proved to be genuine. Much of what is called Aristotelianism is entirely foreign to the spirit of the teaching of Aristotle. The Aristotelians of the Middle Ages were mainly dialecticians, and almost wholly concerned with the formulæ of syllogistic inference, and without real sympathy with, or knowledge of, his system. Much, too, that was attributed to him, and which was venerated accordingly, is undoubtedly spurious. The fame of the Master has consequently suffered at the hands of those who, calling themselves Peripatetics, were in no proper sense followers of his method or interpreters of his dogma. Aristotle affirmed that natural science can only be founded upon a knowledge of facts, and facts can only be ascertained through observation and experiment. He illustrates this particularly by a reference to astronomy, “which,” he says, “is based on the observation of astronomical phenomena, and it is the case with every branch of science or art.” It is erroneous and unjust, therefore, to suppose that Aristotle’s philosophy, as he taught it, is opposed to the true methods of science. A knowledge of Aristotle’s works was transferred by Byzantine writers to Egypt; and, when that land was overrun by the Arabs in the seventh century, they adopted his system, spreading it abroad wherever their conquests extended. In the eighth century they carried it into Spain, where it flourished throughout their occupation of that country. From the ninth to the eleventh century the greater part of Europe was in a state of barbarism. The Moslem caliphate in Spain, under the beneficent rule of Jusuf and Jaküb, alone preserved science from extinction. Cordova, Seville, Grenada, and Toledo were the chief seats of learning in Western Europe; and it was mainly through “the perfect and most glorious physicist,” the Moslem Ibn-Roshd—better known as Averroes—(1126–1198), that Christian scholiasts like Roger Bacon acquired their knowledge of the philosophical system of Aristotle, and mainly through the Moslems Geber and Avicenna that they gained acquaintance with the science of the East.