Geography

​But while this advantage is with respect to practical actions, our treatise possesses also a speculation that is not of a mean sort, part of which is scientific, mathematical, and physical, and the other part lies in history and myths, which are of no use for practical actions. For example, if one were to tell of the wanderings of Odysseus, Menelaus, and Jason, he would seem to contribute nothing to the wisdom which the man of action seeks, unless he should mingle with them useful examples from actual facts; yet it would afford a not unliberal pastime to one who applies himself to the places that provided the material for the myths. For this, too, men of action seek for the sake of reputation and pleasure, but not to a great extent; for they are more earnest, as is natural, about what is useful. Therefore, the geographer too must care more for the former than the latter. And it is the same way also concerning history and mathematics; for of these too, we must always grasp the useful and the more credible.

​But most of all, as has been said, there is need of geometry and astronomy for such an undertaking. And there is indeed truly need; for figures, climates, sizes, and the other things appropriate to these, it is not possible to grasp properly without such a method. But, just as they demonstrate the facts concerning the measurement of the whole earth in other works, so here we must assume them and believe what has been demonstrated there; and assume also that the universe is spherical, and that the surface of the earth is also spherical, and, even prior to these, the downward motion of bodies toward the center. Now, since these things are near to sensation or common notions, if at all, let us point out briefly a few things in outline; for instance, that the earth is spherical: the reminder of this comes from afar from the motion toward the center and from the fact that each body inclines toward its own center of gravity, but from nearby, from the phenomena observed at sea and in the sky; for indeed both sensation and common notion can bear witness. For clearly the curvature of the sea blocks the view of those who sail, so that they cannot see distant lights that are elevated to the level of their eyes. At any rate, if elevated above the eye, they become visible, although they are farther away from it; and likewise, when the eye itself is elevated, it sees things that were previously hidden. Which the Poet also shows; for such is also this passage: looking very sharply forward, being lifted up by a great wave. And to those who sail toward land, the parts near the shore always reveal themselves more and more, and what at first appeared low is lifted higher. And the revolution of the heavenly bodies is manifest, both in other ways and from the shadow-casters; and from these immediately the conception is suggested that if the earth were rooted to infinity, such a revolution would not occur. And the facts about climates are demonstrated in the treatises on habitations.