1. They say that the sun has a motion of its own and does not turn
with the universe. For if it remained fixed in the heavens all
days and nights would be equal, but since we see that it will set
to-morrow in a different place from where it set yesterday, it is
plain that it has a motion of its own and does not move with the
universe. For it accomplishes its yearly orbits by varying courses,
on account of the changes of the seasons.
2. For going further to the south it makes winter, in order that the
land may be enriched by winter rains and frosts. Approaching the
north it restores the summer, in order that fruits may mature, and
what is green in the damp weather may ripen in the heat.