[p. 45] braces the body, used frequently it relaxes. Since, however, nature and not number should be the standard of frequency, regard being had to age and constitution, concubitus can be recognized as harmless when followed neither by languor nor by pain. The use is worse in the day-time, and safer by night; but care should be taken that by day it be not immediately followed by a meal, and at night not immediately followed by work and watching. Such are the precautions to be observed by the strong, and they should take care that whilst in health their defences against ill-health are not used up.
2 The weak, however, among whom are a large portion of townspeople, and almost all those fond of letters, need greater precaution, so that care may re-establish what the character of their constitution or of their residence or of their study detracts. Anyone therefore of these who has digested well may with safety rise early; if too little, he must stay in bed, or if he has been obliged to get up early, must go to sleep again; he who has not digested, should lie up altogether, and neither work nor take exercise nor attend to business. He who without heartburn eructates undigested food should drink cold water at intervals and none the less exercise self-control.
He should also reside in a house that is light, airy in summer, sunny in winter; avoid the midday sun, the morning and evening chill, also exhalations from rivers and marshes; and he should not often expose himself when the sky is cloudy to a sun that breaks through . . ., lest he should be affected alternately by cold and heat — a thing which excites
