HONAIN, a Christian physician, flourished at Baghdad in the middle of the ninth century. He travelled in Greece that he might perfect himself in the language, and he read the works of all the great writers of that country. On his return to Baghdad he was invited by the Caliph to undertake the translation of the Greek authors. His best known translation is _The Aphorisms of Hippocrates with the Commentaries of Galen_. He wrote on midwifery, and was a good oculist. SERAPION THE ELDER (of Damascus), who flourished in the ninth century, was a Syrian physician, of whom little or nothing is known except that he wrote two works, one of which is in the Bodleian in MS., entitled _Aphorismi magni momenti de Medicina Practica_. The other is entitled _Kunnásh_, and has been translated into Latin. The classical period of Arabian medicine begins with— RHAZES, “the Arabic Galen,” whose real name was _Abú Becr Mohammed Ibn Zacaríyá Ar-Razi_, was born at Rai, near Chorásán, probably about the middle of the ninth century after Christ. His famous work, _On the Small Pox and Measles_, was translated from the original Arabic into Syriac, and from that language into Greek. This is the first extant medical treatise in which the small-pox is certainly mentioned.[711] This famous book has been published in various languages about thirty-five times; a greater number of editions, says Dr. Greenhill, than almost any other ancient medical treatise has passed through. He was skilled in philosophy, astronomy, and music, as well as in medicine, which he began to study when he was forty years old. He became one of the most celebrated physicians of his time, and was appointed physician to the hospital at Rai, and afterwards to that of Baghdad, where he became so famous as a teacher that pupils flocked to him from all parts. He afterwards resided at the court of Cordova. He died at an advanced age about A.D. 932. More than two hundred titles of his works have been preserved; but his small-pox treatise is the only one which has been published in the original Arabic. It is a remarkable and a very interesting fact that he explained the nature of the small-pox and measles by the theory of fermentation.[712]