words, the first describing the path of the equator, the second, the path
of the ecliptic. The motion of the second is controlled by the first, and
hence the oblique line in which the planets are supposed to move becomes a
spiral. The motion of the same is said to be undivided, whereas the inner
motion is split into seven unequal orbits--the intervals between them being
in the ratio of two and three, three of either:--the Sun, moving in the
opposite direction to Mercury and Venus, but with equal swiftness; the
remaining four, Moon, Saturn, Mars, Jupiter, with unequal swiftness to the
former three and to one another. Thus arises the following progression:--
Moon 1, Sun 2, Venus 3, Mercury 4, Mars 8, Jupiter 9, Saturn 27. This
series of numbers is the compound of the two Pythagorean ratios, having the
same intervals, though not in the same order, as the mixture which was
originally divided in forming the soul of the world.

Plato was struck by the phenomenon of Mercury, Venus, and the Sun appearing
to overtake and be overtaken by one another. The true reason of this,
namely, that they lie within the circle of the earth's orbit, was unknown
to him, and the reason which he gives--that the two former move in an
opposite direction to the latter--is far from explaining the appearance of
them in the heavens. All the planets, including the sun, are carried round
in the daily motion of the circle of the fixed stars, and they have a
second or oblique motion which gives the explanation of the different
lengths of the sun's course in different parts of the earth. The fixed
stars have also two movements--a forward movement in their orbit which is
common to the whole circle; and a movement on the same spot around an axis,
which Plato calls the movement of thought about the same. In this latter
respect they are more perfect than the wandering stars, as Plato himself
terms them in the Timaeus, although in the Laws he condemns the appellation
as blasphemous.