Cassii iatrosophistae naturales et medicinales quaestiones LXXXIIII, circa hominis naturam & morbos aliquot

has the power of relaxing rather than pressing. Should it be said to this that pleasure does not entirely accompany sleep, but that it happens incidentally that the sleeper enjoys pleasure because the parts of the body are restored, each to its own state, as the weariness the fatigue caused by the day's activity is relieved, which the actions of the waking person had caused? Furthermore, that pleasure is not perpetually generated by the diffusion of the body is apparent from the affection of thirst. For this arises because of dryness. And every dryness brings about densification. Yet, when we are thirsty and drink cold water, we are seized by great pleasure, even though the pre-existing densification is increased by the admixture of the cold. Therefore, just as we do not say that cold water relaxes because it soothes the body with pleasure, so neither should sleep be called relaxing just because it produces pleasure. But pleasure indeed occurs in sleep for the aforementioned reason. Now, navigation or being carried in a scapha a light boat or skiff, can indeed disperse gross bodies, but it densifies the sensitive spirit, disturbing and constipating it while the remaining humors rest without motion: and it happens that sleep supervenes when the spirit is constipated. Yet it is not a wonder if the same agitation both disperses the body and densifies the sensitive spirit, as we have said. For just as hot water lifts our relaxed bodies into a larger volume, yet quenches fire when poured upon it, so also gestation the act of being carried or rocked produces contrary effects, and indeed one will find many things producing conflicting results.