bodily labour is to health, and that exercise is the most effectual
physic. I have described in my hundred and fifteenth paper, from the
general structure and mechanism of an human body, how absolutely
necessary exercise is for its preservation; I shall in this place
recommend another great preservative of health, which in many cases
produces the same effects as exercise, and may, in some measure, supply
its place, where opportunities of exercise are wanting.

18. The preservative I am speaking of is temperance, which has those
particular advantages above all other means of health, that it may be
practised by all ranks and conditions, at any season, or in any place.
It is a kind of regimen into which every man may put himself, without
interruption to business, expense of money, or loss of time. If exercise
throws off all superfluities, temperance prevents them: if exercise
clears the vessels, temperance neither satiates nor over-strains them;
if exercise raises proper ferments in the humours, and promotes the
circulation of the blood, temperance gives nature her full play, and
enables her to exert herself in all her force and vigour: if exercise
dissipates a growing distemper, temperance starves it.

19. Physic, for the most part, is nothing else but the substitute of
exercise or temperance. Medicines are indeed absolutely necessary in
acute distempers, that cannot wait the slow operations of these two
great instruments of health: but did men live in an habitual course of
exercise and temperance, there would be but little occasion for them.
Accordingly we find that those parts of the world are the most healthy,
where they subsist by the chase; and that men lived longest when their
lives were employed in hunting, and when they had little food besides
what they caught.