The parts are identical, so if it were not for the illumination of the planets, their advance and retardation would not be known, and they are what the sight perceives and its progress and return. So the owners of the science of form gave the celestial bodies a permissible arrangement possible within the rule of reason. The knowledge of this gave them the observation of the planets, their progress, their advance, their retardation, their slowness, and their speed, and they added This is due to the spheres revolving in them, and they made the planets in the heavens like moles on the surface of the human body, or like leprosy due to their whiteness, and everything they said gives the balance of their movements, and if God Almighty had done that as they mentioned, the course would have been the same course, and for this reason they are correct in the knowledge of eclipses and the entry of the spheres into one another, and likewise the paths that enter into one another. Some in