Twenty-four centuries ago a line of Æschylus--"Egypt nurtured by the snow"--embodied a geographical theory which descended from Heaven knows what early folk-wandering. Aristotle with his _'aryuroun oros_, the Mountain of Silver from which the Nile flowed, continued the tradition in literature. Meantime Sabæan Arabs, trading along the east coast of Africa, and making expeditions to the interior, came back with stories of great inland seas and snow mountains near them. What they saw may have been only Kilimanjaro and Kenia, but the popular acceptance of their reports points to the earlier tale linking the snows with the Nile valley. Greek and Roman travellers spread the rumour, and presently it found its way, probably through Marinus of Tyre, into the pages of the geographer Ptolemy. Ptolemy had no doubt about these snows. He called them the Mountains of the Moon, and definitely fixed them as the source of the river of Egypt. For centuries after him the question slumbered, and men were too busied with creeds and conquests to think much of that fount of the Nile which Alexander the Great saw in his dreams. When the exploration of Equatoria began in last century the story revived, and the discovery of Kenia and Kilimanjaro seemed to have settled the matter. It was true that these mountains were a long way from the Nile watershed, but then Ptolemy had never enjoyed much of a reputation for accuracy. Still doubt remained in some minds, and explorers kept their eyes open for snow mountains which should actually feed the Nile, since, after all, so ancient a tradition had probably some ground of fact. Speke in 1861 thought he had discovered them in the chain of volcanoes between Lake Kivu and Lake Albert Edward, but these mountains held no snow. He received a hint, however, which might have led to success, for he heard from the Arabs of Unyamwezi of a strange mountain west of Lake Victoria, seldom visible, covered with white stuff, and so high and steep that no man could ascend it. In 1864 Sir Samuel Baker was within sight of Ruwenzori, and actually saw dim shapes looming through the haze, to which he gave the name of "Blue Mountains."