What metaphors are used in The Discarded Image: An Introduction to Medieval and Renaissance Literature by C. S. Lewis?

In Chapter Five, it is noted that much like the modern world conceives of physical objects "obeying laws," the Medievals spoke, for example, of a stone "desiring" to travel towards the Earth. In neither case, should the metaphor be taken literally. The "desires" or inclinations of physical objects depended upon their elemental make-up—whether their composition included earth, wind, air, or fire, and in what proportions. Earth inclined downwards, for example, while fire inclined upwards. The Medievals also conceived of a fifth element called aether, but it only existed outside of the sublunary sphere; that is, one would have to travel outside of the orbit of the moon to find it.