Such, however, was the credit and prevalence of this system that, fifteen hundred years afterwards, Tasso completely imitated Virgil in his fourteenth canto, while imitating at the same time with far greater felicity Ariosto. An old Christian magician conducts underground the two knights who are to bring back Rinaldo from the arms of Armida, as Melissa had rescued Rogero from the caresses of Alcina. This venerable sage makes Rinaldo descend into his grotto, from which issue all the rivers which refresh and fertilize our earth. It is a pity that the rivers of America are not among the number. But as the Nile, the Danube, the Seine, the Jordan, and the Volga have their source in this cavern, that ought to be deemed sufficient. What is still more in conformity to the physics of antiquity is the circumstance of this grotto or cavern being in the very centre of the earth. Of course, it is here that Maupertuis wanted to take a tour. After admitting that rivers spring from mountains, and that both of them are essential parts of this great machine, let us beware how we give in to varying and vanishing systems. When Maillet imagined that the sea had formed the mountains, he should have dedicated his book to Cyrano de Bergerac. When it has been said, also, that the great chains of mountains extend from east to west, and that the greatest number of rivers also flow always to the west, the spirit of system has been more consulted than the truth of nature. With respect to mountains, disembark at the Cape of Good Hope, you will perceive a chain of mountains from the south as far north as Monomotapa. Only a few persons have visited that quarter of the world, and travelled under the line in Africa. But Calpe and Abila are completely in the direction of north and south. From Gibraltar to the river Guadiana, in a course directly northward, there is a continuous range of mountains. New and Old Castile are covered with them, and the direction of them all is from south to north, like that of all the mountains in America. With respect to the rivers, they flow precisely according to the disposition or direction of the land. The Guadalquivir runs straight to the south from Villanueva to San Lucar; the Guadiana the same, as far as Badajos. All the rivers in the Gulf of Venice, except the Po, fall into the sea towards the south. Such is the course of the Rhone from Lyons to its mouth. That of the Seine is from the north-northwest. The Rhine, from Basle, goes straight to the north. The Meuse does the same, from its source to the territory overflowed by its waters. The Scheldt also does the same.