All, therefore, who hold that the heaven is in the form of a sphere, say that it is equally removed and distant from the earth at all points, whether above, or sideways, or below. And by ‘below’ and ‘sideways’ I mean all that comes within the range of our senses. For it follows from what has been said, that the heaven occupies the whole of the upper region and the earth the whole of the lower. They say, besides, that the heaven encircles the earth in the manner of a sphere, and bears along with it in its most rapid revolutions sun, moon and stars, and that when the sun is over the earth it becomes day there, and when it is under the earth it is night. And, again, when the sun goes under the earth it is night here, but day yonder.