As to the geographical discovery, how was it possible that all the marvels of the Mediterranean and Black Seas, the sorcerers, enchanters, giants, and monsters of the deep, should survive when those seas were daily crossed in all directions? How was it possible that the notion of a flat earth, bounded by the horizon and bordered by the circumfluous ocean, could maintain itself when colonies were being founded in Gaul, and the Phoenicians were bringing tin from beyond the Pillars of Hercules? Moreover, it so happened that many of the most astounding prodigies were affirmed to be in the track which circumstances had now made the chief pathway of commerce. Not only was there a certainty of the destruction of mythical geography as thus presented on the plane of the earth looking upward to day; there was also an imminent risk, as many pious persons foresaw and dreaded, that what had been asserted as respects the interior, or the other face looking downward into night, would be involved in the ruin too. Well, therefore, might they make the struggle they did for the support of the ancient doctrine, taking the only course possible to them, of converting what had been affirmed to be actual events into allegories, under which, they said, the wisdom of ancient times had concealed many sacred and mysterious things. But it is apparent that a system forced to this necessity is fast hastening to its end. [Sidenote: Fictitious marvels replaced by grand actualities.] Nor was it maritime discovery only that thus removed fabulous prodigies and gave rise to new ideas. In due course of time the Macedonian expedition opened a new world to the Greeks and presented them with real wonders; climates in marvellous diversity, vast deserts, mountains covered with eternal snow, salt seas far from the ocean, colossal animals, and men of every shade of colour and every form of religion. The numerous Greek colonies founded all over Asia gave rise to an incessant locomotion, and caused these natural objects to make a profound and permanent impression on the Hellenic mind. If through the Bactrian empire European ideas were transmitted to the far East, through that and other similar channels Asiatic ideas found their way to Europe. [Sidenote: Development of Mediterranean commerce.]