M. Vitruvius per Iocundum solito castigatior factus cum figuris et tabula ut iam legi et intelligi possit

Concerning the selection of salubrious places, and what harms salubrity, and from where light should be captured. Chapter IV.

In the walls themselves, these will be the principles. First, the selection of the most salubrious place. It will be high and not foggy, not frosty, and looking toward a region of the sky that is neither sweltering nor cold, but temperate. Next, if the vicinity of marshes is avoided. For when morning breezes reach the town with the rising sun, and the fogs arising from them are joined, and they scatter the poisonous breaths of marsh beasts mixed with the fog into the bodies of the inhabitants, they will make the place pestilent. Likewise, if the walls are next to the sea and look toward the south or west, they will not be salubrious: because during the summer, the southern sky grows warm at the rising sun and burns at midday. Likewise, that which looks to the west grows warm when the sun has risen, is hot at midday, and burns in the evening. Therefore, by the changes of heat and refrigeration, the bodies that are in those places are vitiated. This, however, can be observed even from things that are not animals. For in roofed wine cellars, no one captures light from the south or the west, but from the north: that region does not receive changes at any time, but is firm, perpetual, and immutable. For this reason, also, granaries that look toward the course of the sun quickly change their quality, and provisions and fruits which are not placed in that part of the sky which is turned away from the course of the sun are not preserved for long. For heat, when it cooks, always strips the air of its firmness, and by sucking out natural virtues with scorching vapors, it dissolves them and makes them weak, softening them with heat: just as we observe in iron, which, whatever its nature—hard—is heated by the vapor of fire in furnaces and softens so that it may be easily fashioned into any kind of form; and the same when it is soft and glowing, if it is cooled by dipping in cold water, it hardens and is restored to its ancient property. It is also possible to consider that these things are so from the fact that in summer, not only in pestilent places but also in salubrious ones, all bodies become weak from the heat; and during the winter, even the most pestilent regions are made salubrious, because they are solidified by cooling. No less, those bodies that are transferred from cold regions into hot ones cannot last, but are dissolved; those from hot places, however, into regions under the northern cold, not only do not suffer health problems from the change of place, but are even strengthened. Therefore, it seems that in placing walls, one must be wary of those regions that can scatter heat and breath into human bodies. For since all bodies are composed from the principles which the Greeks call stoicheia elements—that is, from heat, moisture, earth, and air—and from these mixtures, the natural temperature forms the qualities of all animals in the world in general; therefore, in those bodies where heat exceeds the principles, it then kills and dissolves the rest with fervor. These vices are made by the heat... The text cuts off mid-sentence.