[147] Again, he has divided things so as to make his divisions equal in point of magnitude; such as the parallel cycles in heaven, and those which belong to the equinoxes both of spring and autumn, and those which belong to the winter and summer solstice. And on the earth he has divided the zones, two being equal to one another, which being placed close to the poles are frozen with cold, and on this account are uninhabitable. And two he has placed on the borders between these two and the torrid zone, and these two they say are the abode of a happy temperature of the air, one of them lying towards the south and the other towards the north.