The orrery or picture of the heavens given in the Republic differs in its
mode of representation from the circles of the same and of the other in
the Timaeus. In both the fixed stars are distinguished from the planets,
and they move in orbits without them, although in an opposite direction:
in the Republic as in the Timaeus (40 B) they are all moving round the
axis of the world. But we are not certain that in the former they are
moving round the earth. No distinct mention is made in the Republic of the
circles of the same and other; although both in the Timaeus and in the
Republic the motion of the fixed stars is supposed to coincide with the
motion of the whole. The relative thickness of the rims is perhaps
designed to express the relative distances of the planets. Plato probably
intended to represent the earth, from which Er and his companions are
viewing the heavens, as stationary in place; but whether or not herself
revolving, unless this is implied in the revolution of the axis, is
uncertain (cp. Timaeus). The spectator {clxviii} may be supposed to look
at the heavenly bodies, either from above or below. The earth is a sort of
earth and heaven in one, like the heaven of the Phaedrus, on the back of
which the spectator goes out to take a peep at the stars and is borne
round in the revolution. There is no distinction between the equator and
the ecliptic. But Plato is no doubt led to imagine that the planets have
an opposite motion to that of the fixed stars, in order to account for
their appearances in the heavens. In the description of the meadow, and
the retribution of the good and evil after death, there are traces of
Homer.