Bathing can be either in hot water or cold. Bathing in hot water initially strengthens animal strength and the “need for cooling,” but when it dissolves the juices excessively, the pulse weakens. Galen said: “Then the pulse is small, slow and rare,” and we affirm: as for the weakening and reduction of the pulse, this happens necessarily, but when hot water, due to its collateral heat, produces heating inside the body, then it sometimes does not remains long, and the water is overcome by the need of its nature, that is, the need to cool, and sometimes the heating lasts and seems to be preserved. If the influence of a secondary quality overcomes, then the pulse becomes fast and frequent, and if the need of nature overcomes, the pulse becomes slow and rare. When the collateral heating from the hot water reaches an extreme degree and dissolves the animal strength to such an extent that the person approaches fainting, the pulse also becomes slow and rare.
As for bathing in cold water, when the cold penetrates deeply into the body, it weakens the pulse and makes it small, at the same time causing it to be rare and slow. If the cold does not penetrate the body, but, on the contrary, collects heat, then animal strength increases, and the pulse becomes a little larger, and the speed and frequency decrease. Regarding the types of water that are available in baths, it should be said that drying waters increase the hardness of the pulse and reduce its size, and warming waters increase the speed of the pulse, but dissolve animal strength, and something happens that we have already finished talking about.