Platonicae quaestiones

Plutarch

Plutarch. Plutarch's Morals, Vol. V. Goodwin, William W., editor; Brown, R., translator. Boston: Little, Brown, and Company; Cambridge: Press of John Wilson and Son, 1874.

How respiration is made by the reaction of the air,

he has sufficiently shown. But the rest, he says, seem to be done miraculously, but really the bodies thrust each other aside and change places with one another; while he has left for us to determine how each is particularly done.

As to cupping-glasses, the case is thus: the air next to the flesh being comprehended and inflamed by the heat, and being made more rare than the pores of the brass, does not go into a vacuum (for there is no such thing), but into the air that is without the cupping-glass, and has an impulse upon it. This air drives that before it; and each, as it gives way, strives to succeed into the place which was vacuated by the cession of the first. And so the air approaching the flesh comprehended by the cupping-glass, and exciting it, draws the humors into the cupping-glass.

Swallowing takes place in the same way. For the cavities about the mouth and stomach are full of air; when therefore the meat is squeezed down by the tongue and tonsils, the elided air follows what gives way, and also forces down the meat.

Weights also thrown cleave the air and dissipate it, as they fall with force; the air recoiling back, according to its natural tendency to rush in and fill the vacuity, follows the impulse, and accelerates the motion.