Bern, Burgerbibliothek, Cod. 402

Why the sun darkens the flesh, but fire does not.

but fire does not. For it happens that the heat of the sun, being thin and soft, is introduced little by little into the pores, and, as it were, evaporates and burns the surface; for this reason, it is generally painless. But the heat of fire, being thicker and more violent, warms the whole flesh more thoroughly, and as the blood rises, it does not retain its color. However, if one were to use [the fire] more violently, then burning indeed darkens the skin, for things scorched by fire and, in general, things that are burned, turn black. For this reason, the Phocaeans original: "Φωκαΐδες" — possibly a reference to a specific group or a local term for a type of skin condition/tanning sometimes have such a color, as if the fire were being extinguished, just as in the case of coals. For nothing is black without moisture, but rather because everything is burnt up when and turned to ash, just like bones. The common saying about earthenware—that fire blackens it while not blackening the flesh—is either untrue or not analogous. For flame sometimes blackens, carrying up soot and smoke, just as it does with wood, earthenware, and walls, and as it appears to do similarly with coals. Why smoke blackens coals. For the smoke is carried up, bringing with it much earthy material. At the same time, not all the moisture is burnt up because it cannot be, and for this reason, it is heavier than the air; for as such vapor is carried up, it draws the breath and is fled from at a distance. For this reason, it weighs down the heads and the entire body. These, then, are the causes one must assume. If, however, the heat occurs in different kinds of matter, such as when it is in moisture or dryness, a difference arises, for many things cannot be done by one [type of heat] that the other does not seem to possess less strongly.