Plutarch's Rules for the Preservation of Health (26-27)

ZEUXIPPUS. I have heard that Tiberius Caesar was wont to say, that he was a ridiculous man that held forth his hand to a physician after sixty. But it seems to me to be a little too severely said. But this is certain, that every man ought to have skill in his own pulse, for it is very different in every man; neither ought he to be ignorant of the temper of his own body, as to heat and cold, or what things do him good, and what hurt. For he has no sense, and is both a blind and lame inhabitant of his body, that must learn these things from another, and must ask his physicians whether it is better with him in winter or summer; or whether moist or dry things agree best with him, or whether his pulse be frequent or slow. For it is necessary and easy to know such things by custom and experience. It is convenient to understand more what meats and drinks are wholesome than what are pleasant, and to have more skill in what is good for the stomach than in what seems good to the mouth, and in those things that are easy of digestion than in those that gratify our palate. For it is no less scandalous to ask a physician what is easy and what is hard of digestion, and what will agree with your stomach and what not, than it is to ask what is sweet, and what bitter, and what sour. They nowadays correct their cooks, being able well enough to tell what is too sweet, too salt, or too sour, but themselves do not know what will be light or easy of digestion, and agreeable to them. Therefore in the seasoning of broth they seldom err, but they do so scurvily pickle themselves every day as to afford work enough for the physician. For that pottage is not accounted best that is the sweetest, but they mingle bitter and sweet together. But they force the body to partake of many, and those cloying pleasures, either not knowing, or not remembering, that to things that are good and wholesome nature adds a pleasure unmingled with any regret or repentance afterward. We ought also to know what things are cognate and convenient to our bodies, and be able to direct a proper diet to any one upon any change of weather or other circumstance.

ZEUXIPPUS. As for those inconveniences which sordidness and poverty bring upon many, as gathering of fruit, continual labor, and running about, and want of rest, which fall heavy upon the weaker parts of the body and such as are inwardly infirm, we need not fear that any man of employ or scholar — to whom our present discourse belongs — should be troubled with them. But there is a severe sort of sordidness as to their studies, which they ought to avoid, by which they are forced many times to neglect their body, oftentimes denying it a supply when it has (lone its work, making the mortal part of us do its share in work as well as the immortal, and the earthly part as much as the heavenly. But, as the ox said to his fellow-servant the camel, when he refused to ease him of his burthen, It won’t be long before you carry my burthen and me too: which fell out to be true, when the ox died. So it happens to the mind, when it refuses that little relaxation and comfort which it needs in its labor; for a little while after a fever or vertigo seizes us, and then reading, discoursing, and disputing must be laid aside, and it is forced to partake of the body’s distemper. Plato therefore rightly exhorts us not to employ the mind without the body, nor the body without the mind, but to drive them equally like a pair of horses; and when at any time the body toils and labors with the mind, then to be the more careful of it, and thus to gain its wellbeloved health, believing that it obliges us with the best of things when it is no impediment to our knowledge and enjoyment of virtue, either in business or discourse.