CHAPTER I INTRODUCTION : THERE is a certain analogy between civilization and an infectious disease. Both pass from one community to another by contact, and whenever either breaks out, one of our first thoughts is, Where did the infection come from? In both alike there is the unanswered question, Where did it first originate? Do all outbreaks trace back to one primary source, or have there been several independent starting points? In reading the autobiography of that distinguished Orientalist Sir Denison Ross, there is a letter received from some inquirer which contains the sentence remarking what a good thing it would be if we could find out "how, and in what form, the Greek and Latin writers found their way to the ken of the Arab or Persian or Turkish student" (Sir Denison Ross, Both Ends of the Candle, n. d., p. 286). The author of the book makes no comment on this letter, but it may be noted that the way in which Greek literature passed to the Arabs and Persians, thence