Daily observation demonstrates that the human structure, even in its
most perfect formation is liable to lesions of organization and
derangment of function, producing that state of the system in which
its usual actions or perceptions are either interrupted or attended
with pain--this state is called disease. Every animal carries within
itself the germ of its own destruction, or, in other words, it is
formed for a limited existence. Many diseases, therefore arise
spontaneously, or without any assignable external cause; but many more
are produced by causes, over which we have some control, and perhaps
the chief source of the physical ills to which we are liable, is the
deviation we make from the simplicity of nature. The injurious
influence that domestication has upon the health of the lower animals
is very strikingly apparent; and in proportion as their subjugation is
more complete, and their manner of life differs more widely from that
which is natural to them, so are their diseases more numerous and
severe. The diseases of our more valuable domestic animals are
sufficiently numerous and important to employ a particular class of
men; and the horse alone has professional assistance appropriated to
him. Men of education and talent have devoted themselves to the
investigation of the diseases of this noble and useful creature. The
poor little canary birds confined in their prisons, are very liable to
disease, more especially inflammation of the bowels, asthma, epilepsy,
and soreness of the bill. No animal deviates so far from the
simplicity of nature in its habits, as man; none is placed under the
influence of so many circumstances, calculated to act unfavourably
upon the frame. His morbid affections are hence abundant and
diversified, as may be seen by referring to the different nosological
arrangements; these long catalogues of diseases affording strong
evidence that man has not carefully followed that way of life which
has been marked out for him by nature. The crowded state of the
inhabitants of large cities; the injurious effects of an atmosphere
loaded with impurities; sedentary occupations; various unwholesome
avocations; intemperance in food; stimulating drinks; high-seasoned
and indigestible viands (and these taken hastily in the short
intervals allowed by the hurry and turmoil of business); the constant
inordinate activity of the great central circulation, kept up by the
double impulse of luxurious habits and high mental exertions; the
violent passions by which we are agitated and enervated; the various
disappointments and vexations to which all are liable, reacting upon
and disturbing the whole frame; the delicacy and sensibility to
external influences, caused by heated rooms, too warm clothing, and
other indulgencies; are all contrary to the voice of nature, and they
produce those morbid conditions of the system which a more simple and
uniform mode of living would prevent. Our associates of the animal
kingdom do not escape the influence of such causes: the mountain
shepherd and his dog are equally hardy, and form an instructive
contrast between a delicate lady and her lap-dog; the extreme point of
degeneracy and imbecility of which each race is susceptible. In the
early ages of society man enjoyed long life, his manner of living was
simple, his food, habitation, and pursuits, were all calculated to
fortify the body, and no anxious cares disturbed his mind.
_Curtis's Essay on the Deaf and Dumb._
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