By the advent of Islam, the Arabic language became the academic language and most of the rich literature written in Greek, Persian or Hindi was translated in Arabic. This paper investigates the medium and elements of transmission of Greek Literature into Arabic language. A large number of Greek sources were translated into Arabic language during the Abbasid rule. The Arabs translated these Greek sources and then learned over again all they had already learned, correcting and verifying their earlier knowledge. Similarly, the Greek works were transmitted via Indian sources which might have been derived by Greek heritage. Thus, there came a second channel of transmission indirectly through India, mathematical and astronomical work, all a good deal developed by Indian scholars, but certainly developed from material obtained from Alexandria in the first place. This material had passed to India by the sea route which connected Alexandria with north-west India. Then there was also another line of passage through India which seems to have had its beginning in the Greek kingdom of Bactria, one of the Asiatic states founded by Alexander the Great, and a land route long kept open between the Greek world and India. Further, there were some scattered minor sources, unfortunately little known, such as the city of Harran, an obstinately pagan Greek colony planted in the middle of a Christian area, which probably made its contribution, though on a smaller scale. The article shows that the mentioned elements played a great role in transferring Greek heritage into Arabic heritage. [ABSTRACT FROM AUTHOR]