In the four hundred and thirteenth year of the Christian Era, some three hundred miles above Alexandria, the young monk Philammon was sitting on the edge of a low range of inland cliffs, crested with drifting sand. Behind him the desert sand-waste stretched, lifeless, interminable, reflecting its lurid glare on the horizon of the cloudless vault of blue. At his feet the sand dripped and trickled, in yellow rivulets, from crack to crack and ledge to ledge, or whirled past him in tiny jets of yel ...