All mixtures of food upon the stomach are bad: and there is not a greater error in an old person than to eat of many dishes at one meal. He must not deceive himself by arguing that they all are innocent: for two things of known qualities will often, on mixing, produce a third that is perfectly different from them both: and these are dangerous trials in an aged person’s stomach. Right management in these articles is nearly as important as a right choice. A regularity of eating is the next care to the selecting proper food; and fixing on a right quantity. CHAP. V. _Of air for elderly persons._ Nothing contributes more to health and long life than pure and good air: but by pure we are not to understand bleak; nor are aged persons at any time to chuse that kind. It is strange so many should live to a great age in London, where the air has neither of these characters; where we breathe smoke, and the mixt stench of a thousand putrifying substances; which cannot evaporate through the thick and foul atmosphere of the place. But though none will question the superior excellence of a clear country air, yet let not him who has attained to a healthy three-score and ten in London, think of leaving it, as a way to continue his days to a longer period. They say use is second nature. It really becomes nature itself: and bad things, to which an old man has been very long accustomed, are often better than sudden changes. It is well known, that many who have reached an uncommon date of life, have perished at last by a rash alteration in their food: and ’tis certain the air is scarce of less consequence. He who would extend the period, and encrease the healthy condition of his days by a country air, should begin at an earlier time: when his constitution can better bear the alteration. In regard to a choice of air, the reason we declare against that which is too bleak is plain; for bleak and cold are always found together. Cold air chills the blood; and in old men we want rather to warm it. This sharp air is natural at the tops of hills: and such situations all old men should avoid. On the contrary, the mildest air of the country is that of vallies; sheltered by rising grounds: but this is usually damp; and more mischief may therefore arise from it than good. The choice rests solely then upon a gentle ascent: the best place of all is toward the bottom of a piece of ground, which does not in any part rise to a very great height: and if there be a running water at the lowest part, it is so far perfect.