Besides, every one of us finds by experience, that bodily exercises, clamors, and whatever other actions by violent motion occasion heat, commonly sharpen our stomachs and get us a better appetite.

Now, as I take it, the most natural and principal nourishment of heat is moisture, as it evidently appears from flames, which increase by the pouring in of oil, and from ashes, which are of the driest things in nature; for after the humidity is consumed by the fire, the terrene and grosser parts remain without any moisture at all.
Add to these, that fire separates and dissolves bodies by extracting that moisture which should keep them close and compact.

Therefore, when we are fasting, the heat first of all forces the moisture out of the relics of the nourishment that remain in the body, and then, pursuing the other humid parts, preys upon the natural moisture of the flesh itself.

Hence the body like clay becoming dry, wants drink more than meat; till the heat, receiving strength and vigor by our drinking, excites an appetite for more substantial food.
QUESTION II.

WHETHER WANT OF NOURISHMENT CAUSETH HUNGER AND THIRST OR THE CHANGE IN THE FIGURES OF THE PORES.
PHILO, PLUTARCH.
After these things were spoke, Philo the physician started the first question, asserting that thirst did not arise from the want of nourishment, but from the different transfiguration of certain passages.
For, says he, this may be made evident, partly from what we see happens to those that thirst in the night, who, if sleep chance to steal upon them, though they did not drink before, are yet rid of their thirst; partly from persons in a fever, who, as soon as the disease abates or is removed, thirst no more.