d that two and two are equal to four, would not have said. But
while he judges of what is best by his palate, he does not look up to
the "palace of heaven," as Ennius calls it.

XIX. For as there are two sorts of stars,[129] one kind of which
measure their journey from east to west by immutable stages, never in
the least varying from their usual course, while the other completes a
double revolution with an equally constant regularity; from each of
these facts we demonstrate the volubility of the world (which could not
possibly take place in any but a globular form) and the circular orbits
of the stars. And first of all the sun, which has the chief rank among
all the stars, is moved in such a manner that it fills the whole earth
with its light, and illuminates alternately one part of the earth,
while it leaves the other in darkness. The shadow of the earth
interposing causes night; and the intervals of night are equal to those
of day. And it is the regular approaches and retreats of the sun from
which arise the regulated degrees of cold and heat. His annual circuit
is in three hundred and sixty-five days, and nearly six hours
more.[130] At one time he bends his course to the north, at another to
the south, and thus produces summer and winter, with the other two
seasons, one of which succeeds the decline of winter, and the other
that of summer. And so to these four changes of the seasons we
attribute the origin and cause of all the productions both of sea and
land.

The moon completes the same course every month which the sun does in a
year. The nearer she approaches to the sun, the dimmer light does she
yield, and when most remote from it she shines with the fullest
brilliancy; nor are her figure and form only changed in her wane, but
her situation likewise, which is sometimes in the north and sometimes
in the south. By this course she has a sort of summer and winter
solstices; and by her influence she contributes to the nourishment and
increase of animated beings, and to the ripeness and maturity of all
vegetables.

XX. But most worthy our admiration is the motion of those five stars
which are falsely called wandering stars; for they cannot be said to
wander which keep from all eternity their approaches and retreats, and
have all the rest of their motions, in one regular constant and
established order. What is yet more wonderful in these stars which we
are speaking of is that sometimes they appear, and sometimes they