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.

CHAPTER XII. INTO HOW MANY CIRCLES IS THE HEAVEN DISTINGUISHED; OR, OF
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.

CHAPTER XIII. WHAT IS THE ESSENCE OF THE STARS, AND HOW THEY ARE
COMPOSED.

Thales affirms that they are globes of earth set on fire. Empedocles,
that they are fiery bodies arising from that fire which the aether
embraced within itself, and did shatter in pieces when the elements were
first separated one from another. Anaxagoras, that the circumambient
aether is of a fiery substance, which, by a vehement force in its
whirling about, did tear stones from the earth, and by its own power
set them on fire, and establish them as stars in the heavens. Diogenes
thinks they resemble pumice stones, and that they are the breathings
of the world; again he supposeth that there are some invisible stones,
which fall sometimes from heaven upon the earth, and are there quenched;
as it happened at Aegos-potami, where a stony star resembling fire did
fall. Empedocles, that the fixed stars fastened to the crystal, but the
planets are loosened. Plato, that the stars for the most part are of a
fiery nature, but they are made partakers of another element, with
they are mixed after the resemblance of glue. Zenophanes, that they are
composed of inflamed clouds, which in the daytime are quenched, and in
the night are kindled again. The like we see in coals; for the rising
and