The subject proposed in the following pages is the history of the cultural transmission by which Greek philosophy and science were passed from Hellenistic surroundings to the Syriac speaking community, thence to the Arabic speaking world of Islam, and so finally to the Latin Schoolmen of Western Europe. That such a transmission did take place is known even to the beginner in mediæval history, but how it happened, and the influences which promoted it, and the modifications which took place _en route_, appear to be less generally known, and it does not seem that the details, scattered through works of very diverse types, are easily accessible to the English reader. Many historians seem content to give only a casual reference to its course, sometimes even with strange chronological confusions which show that the sources used are still the mediæval writers who had very imperfect information about the development of intellectual life amongst the Muslims. Following mediæval usage we sometimes find the Arabic writers referred to as “Arabs” or “Moors,” although in fact there was only one philosopher of any importance who was an Arab by race, and comparatively little is known about his work. These writers belonged to an Arabic speaking community, but very few of them were actually Arabs. After the later Hellenistic development Greek culture spread outward into the oriental fringe of people who used Syriac, Coptic, Aramaic, or Persian as their vernacular speech, and in these alien surroundings it took a somewhat narrower development and even what we may describe as a provincial tone. There is no question of race in this. Culture is not inherited as a part of the physiological heritage transmitted from parent to child; it is learned by contact due to intercourse, imitation, education, and such like things, and such contact between social groups as well as between individuals is much helped by the use of a common language and hindered by difference of language. As soon as Hellenism overflowed into the vernacular speaking communities outside the Greek speaking world it began to suffer some modification. It so happened also that these vernacular speaking communities wanted to be cut off from close contact with the Greek world because very bitter theological divisions had arisen and had produced feelings of great hostility on the part of those who were officially described as heretics against the state church in the Byzantine Empire. In this present chapter we have to consider three points; in the first place the particular stage of development reached by Greek thought at the time when these divisions took place; secondly the cause of these divisions and their tendencies; and thirdly the particular line of development taken by Hellenistic culture in its oriental atmosphere.