labour; so is the whole soul when it hears it, and the power of all
those spirits flies as it were to the spirit of sense, which receives
the sound.

And the Heaven of Jupiter can be compared to Geometry because of two
properties. The one is, that it moves between two Heavens, repugnant
to its good tempering, namely, that of Mars and that of Saturn. Hence
Ptolemy says, in the book alluded to, that Jupiter is a star of a
temperate complexion, midway between the cold of Saturn and the heat
of Mars. The other is, that amongst all the stars it appears white, as
if silvered. And these things are in the Science of Geometry. Geometry
moves between two things antagonistic to it; as between the point and
the circle, and I term circle freely anything that is round, either a
body or superfices; for, as Euclid says, the point is the beginning of
Geometry, and, according to what he says, the circle is the most
perfect figure in it, which must therefore have reason for its end; so
that between the point and the circle, as between the beginning and
the end, Geometry moves. And these two are antagonistic to its
certainty; for the point by its indivisibility is immeasurable, and
the circle, on account of its arc, it is impossible to square
perfectly, and therefore it is impossible to measure precisely. And
again, Geometry is most white, inasmuch as it is without spot of
error, and it is most certain in itself, and by its handmaid, called
Perspective.

And the Heaven of Saturn has two properties because of which it can be
compared to Astrology. One is the slowness of its movement through the
twelve signs; for twenty-nine years and more, according to the
writings of the Astrologers, is the time that it requires in its
orbit. The other is, that above all the other planets it is highest.