It now only remains for me to take some notice of exercise. Of all
the various methods of preserving health, and of preventing
diseases, which nature has suggested, there is none more efficacious
than exercise; it puts the fluids all in motion, strengthens the
solids, promotes perspiration, and occasions the decomposition of a
larger quantity of atmospheric air in the lungs. Hence, in order to
preserve the health of the body, the author of nature has made
exercise absolutely necessary to the greater part of mankind for
obtaining the means of existence.--Had not exercise been absolutely
necessary for our well-being, says the elegant Addison, nature would
not have made the body so proper for it, by giving such an activity
to the limbs, and such a pliancy to every part, as necessarily
produce those compressions, extensions, contortions, dilatations, and
all other kinds of motions, that are necessary for the preservation
of such a system of tubes and glands.--And that we might not want
inducement to engage us in such exercise of the body as is proper
for its welfare, it is so ordered, that nothing valuable can be
procured without it. Not to mention riches and honors, even food and
raiment are not to be come at without the toil of the hands and
sweat of the brow. Providence furnishes materials, but expects that
we should work them up ourselves. The earth must be laboured before
it gives its increase, and when it is forced into its several
products, how many hands must they pass through before they are fit
for use? Manufactures, trade, and agriculture, naturally employ more
than nineteen parts of the species out of twenty; and as for those
who are not obliged to labour by the condition in which they are
born, they are more miserable than the rest of mankind, unless they
indulge themselves in that voluntary labour which goes by the name
of exercise.