This story was told by Diogenes to a Syrian geographer called Marinus of Tyre, who published it in his geographical works in the first century of the Christian era. The writings of Marinus of Tyre disappeared, probably with the dispersal of the Alexandrian Library, but fortunately for us at the present day all that portion of them dealing with the sources of the Nile was quoted almost _in extenso_ by another geographer, Claudius Ptolemæus, a Greek-Egyptian, born at Ptolemais in the Delta of the Nile, and resident at Alexandria (perhaps in connection with the celebrated Library). Ptolemy (as he is currently and incorrectly called) wrote in about the year 150 A.D., and therefore to Ptolemy is commonly attributed the first clearly expressed theory as to the main origin of the White Nile, the twin lakes (Victoria and Albert), and the great snowy range called the Mountains of the Moon (Ruwenzori).[6] Neither Marinus of Tyre nor Claudius Ptolemæus was the first person to hint at this origin of the Nile. Besides Eratosthenes and Pliny there are indications in various records of the two centuries before Christ that the idea of the White Nile issuing from two great lakes and passing through a vast marshy region before it reached Ethiopia was vaguely known. The idea had perhaps even reached the ears of Cambyses and of such of the earlier Ptolemies as may have cared for geographical speculations. The bearers of the news would undoubtedly have been men of the Gala (Abyssinian, Somali, Cushite) race, who at that distant period of time seem to have freely penetrated through the lands of the brutish and unarmed Negroes. No doubt many a Greek adventurer in passing along the east coast of Africa brought back tidings similar to those of Diogenes, but his grain fell among the rocks, and the only definite record of the existence of this theory as to the Nile’s origin is the story of Diogenes preserved through the industry of Marinus of Tyre and Claudius Ptolemæus of Alexandria. [Illustration: THE COURSE OF THE NILE, ACCORDING TO PTOLEMY. From the oldest version of Ptolemy’s Map in existence, about 930 A.D., preserved in Mount Athos Monastery.]