Nicene and Post-Nicene Fathers, Vol. II:
City of God: Chapter 9

Chapter 9.—Whether We are to Believe in the Antipodes.

But as to the fable that there are Antipodes, that is to say, men on the opposite side of the earth, where the sun rises when it sets to us, men who walk with their feet opposite ours, that is on no ground credible.  And, indeed, it is not affirmed that this has been learned by historical knowledge, but by scientific conjecture, on the ground that the earth is suspended within the concavity of the sky, and that it has as much room on the one side of it as on the other:  hence they say that the part which is beneath must also be inhabited.  But they do not remark that, although it be supposed or scientifically demonstrated that the world is of a round and spherical form, yet it does not follow that the other side of the earth is bare of water; nor even, though it be bare, does it immediately follow that it is peopled.  For Scripture, which proves the truth of its historical statements by the accomplishment of its prophecies, gives no false information; and it is too absurd to say, that some men might have p. 316 taken ship and traversed the whole wide ocean, and crossed from this side of the world to the other, and that thus even the inhabitants of that distant region are descended from that one first man.  Wherefore let us seek if we can find the city of God that sojourns on earth among those human races who are catalogued as having been divided into seventy-two nations and as many languages.  For it continued down to the deluge and the ark, and is proved to have existed still among the sons of Noah by their blessings, and chiefly in the eldest son Shem; for Japheth received this blessing, that he should dwell in the tents of Shem.