The Summary of Physics Restored

59Earth is the densest of the universe's bodies and is therefore regarded as the heaviest and as its centre. Against common opinion, we must hold that its nature is cold in itself and dry accidentally, because it retains more of first matter's opaque and dark nature. Shadow and darkness are hiding places of cold; hence they flee light and stand diametrically opposed to it. Because of its extreme density earth is the mother of shadow and darkness, difficult for light and heat to penetrate, and therefore stiffens with the greatest cold. For this reason black bile must be regarded as the coldest humour of all, because it is subject to earth's dominion, while earth is subject to Saturn, held to be the author of the cold and melancholic temperament. Moreover, things generated from earthy substance in the earth's entrails, such as marble and stones, are cold in nature. Metals must be judged differently, however, because they are of a more airy nature and contain much fire, through sparks of nature's fire poured in from heaven and a sulphurous spirit congealing their moist and cold matter. Mercury, exceeding the others in moisture and cold, owes its coldness to earth and its moisture to water. It is otherwise with things produced in the sea, as is sufficiently evident from ambar, coral and many other products of sea and rivers, which possess a hot temperament. Reason and experience therefore teach us that the greatest cold belongs to earth, not water.