The Summary of Physics Restored

127If any of those four natures inclines towards mutual conversion, the inclination is much stronger in the intermediate pair. Water and air are bound by a greater affinity with each other than with the others, or than the others have with one another. They appear to differ less in qualities than in the intensity and relaxation of qualities, and less in nature than in accidents. For water claims coldness and moisture by Nature’s right and communicates both to the lower region of air through their intercourse. Air possesses scarcely any quality of its own except extreme tenuity, but is capable of being imbued with the rest. For that reason it is of a heavenly nature, which, being in itself most temperate and committed to no particular quality, readily receives and communicates others’ dispositions, influences, and powers—namely those of the heavenly bodies. Density and rarity, which border upon one another when relaxed, seem to establish the chief difference between water and our air. Hence in sacred Genesis we read that God separated waters from waters, as though a division of one nature according to place had occurred, rather than a change according to essence.