The series of Syriac philosophical writers closes with _Gregory Bar Hebraeus_, or _Abu l-Faraj_ in the thirteenth century A.D. whose “Book of the Pupils of the Eyes” is a compendium of logic summarising and explaining the Isagoge, and Aristotle’s Categories, Hermeneutica, Analytica, Topica, and Sophistica Elenchi; his “Book of the Upholding of Wisdom” being a summary introduction to logic, physics, metaphysics, and theology. A third work “The Cream of Science” is an encyclopædia of the Aristotelian philosophy, and this work appears also in an abridged form as the “Business of Businesses.” He was also the translator into Syriac of Dioscorus on simples, and author of a treatise on the medical _Questions_ of Hunayn b. Ishaq, and of a work on geography called “the Ascent of the Spirit.” Although esteemed as one of the greatest Syriac authorities and for centuries holding a place of primary importance, he was in reality no more than a compiler who produced encyclopædic works dealing with the researches of his predecessors. The great importance of the Syriac speaking Christian communities was as the medium whereby Hellenistic philosophy and science was transmitted to the Arabic world. There was no independent development in its Syriac atmosphere, and even the choice of material had already been made by the Hellenists before it passed into Syriac hands. It was now definitely established that the basis of the “humanities” was the Aristotelian logic, and that this as well as all other studies in the work of Aristotle was to be interpreted according to the neo-Platonic commentators. In medicine and chemistry the curriculum of the school of Alexandria was recognised as authoritative and this, in so far as it was based upon Galen and Hippocrates, and upon the teaching of Paul of Aegina in obstetrical medicine, was to the good: but there was a mystical side of Alexandrian science mixed up with astrology, so that particular drugs had to be taken where certain planets were in the ascendant, and such like ideas, which gave a magical tone to Alexandrian and Arabic medicine which was not for its advantage, although it must be remembered that the ready contempt formerly poured upon Arabic science as mere charlatanism is now expressed more cautiously: we are prepared to admit that very much real and valuable work was done in medicine and chemistry, although it is probable that the Egyptian obscurantism did rather tend to hinder the steady development of the sounder tradition derived from Galen and the Greek physicians. We are thus able to understand that “Muslim theology, philosophy, and science put forth their first luxuriant shoots on a soil which was saturated with Hellenistic culture.” (Nicholson: _Mystics of Islam._ London, 1914 p. 9.) The passage of Hellenism took place through five channels:-- (i) The Nestorians who hold the first place as the earliest teachers of the Muslims and the most important transmitters of medicine.