Plutarch's Rules for the Preservation of Health (8-9)

ZEUXIPPUS. But we shall perhaps discourse against pleasures in another place, and show the beauty and dignity that temperance has within itself; but our present discourse is in praise of many and great pleasures. For diseases do not either rob or spoil us of so much business, hope, journeys, or exercise, as they do of pleasure; so that it is no way convenient for those who would follow their pleasure to neglect their health. There are diseases which will permit a man to study philosophy and to exercise any military office, nay, to act the kingly part. But the pleasures and enjoyments of the body are such as cannot be born alive in the midst of a distemperor if they are, the pleasures they afford are not only short and impure, but mixed with much alloy, and they bear the marks of that storm and tempest out of which they rise. Venus herself delights not in a gorged, but in a calm and serene body; and pleasure is the end of that, as well as it is of meat and drink. Health is to pleasure as still weather to the halcyon, giving it a safe and commodious birth and nest. Prodicus seems elegantly enough to have said, that of all sauces fire was the best; but most true it is to say, that health gives things the most divine and grateful relish. For meat, whether it be boiled, roasted, or stewed, has no pleasure or gusto in it to a sick, surfeited, or nauseous stomach. But a clean and undebauched appetite renders every thing sweet and delightful to a sound body, and (as Homer expresses it) devourable.

ZEUXIPPUS. As Demades told the Athenians, who unseasonably made war, that they never treated of peace but in mourning, so we never think of a moderate and slender diet but when we are in a fever or under a course of physic. But when we are in these extremities, we diligently conceal our enormities, though we remember them well enough; yet as many do, we lay the blame of our illness now upon the air, now upon the unhealthfulness of the place or the length of a journey, to take it off from that intemperance and luxury which was the cause of it. As Lysimachus, when he was among the Scythians and constrained by his thirst, delivered up himself and his army into captivity, but afterwards, drinking cold water, cried out, O ye Gods! for how short a pleasure have I thrown away a great felicity! — so in our sickness, we ought to consider with ourselves that, for the sake of a draught of cold water, an unseasonable bath, or good company, we spoil many of our delights as well as our honorable business, and lose many pleasant diversions. The remorse that arises from these considerations wounds the conscience, and sticks to us in our health like a scar, to make us more cautious as to our diet. For a healthful body does not breed any enormous appetite, or such as we cannot prevail with or overcome. But we ought to put on resolution against our extravagant desires or efforts towards enjoyment, esteeming it a low and childish thing to give ear to their complaints and murmurings; for they cease as soon as the cloth is taken away, and will neither accuse you of injustice, nor think you have done them wrong; but on the contrary, you will find them the next day pure and brisk, no way clogged or nauseating. As Timotheus said, when he had had a light philosophic dinner the other day with Plato in the Academy, They who dine with Plato never complain the next morning. It is reported that Alexander said, when he had turned off his usual cooks, that he carried always better with him; for his journeys by night recommended his dinner to him, and the slenderness of his dinner recommended his supper.