HKB
Anaximenes affirms that the circumference of heaven makes the limit of the earth's revolution. Empedocles, that the heaven is a solid substance, and hath the form and hardness of crystal, it being composed of the air compacted by fire, and that in both hemispheres it invests the elements of air and fire. Aristotle, that it is formed by the fifth body, and by the mixture of extreme heat and cold.
THE DIVISION OF HEAVEN.
Thales, Pythagoras, and the followers of Pythagoras do distribute the universal globe of heaven into five circles, which they denominate zones; one of which is called the arctic circle, which is always conspicuous to us, another is the summer tropic, another is the solstice, another is the winter tropic, another is the antarctic circle, which is always out of sight. The circle called the zodiac is placed under the three that are in the midst, and is oblique, gently touching them all. Likewise, they are all divided in right angles by the meridian, which goes from pole to pole. It is supposed that Pythagoras made the first discovery of the obliquity of the zodiac, but one Oenopides of Chios challenges to himself the invention of it.