tainly should,
within the next decade, yield to our attack, as tuberculosis and typhoid
are already beginning to do.

CHAPTER IX

THE NATURAL HISTORY OF TYPHOID FEVER

Why should not a disease have a natural history, as well as an
individual? At first sight, this might appear like a reversion to the
old, crude theory of disease as a demonic obsession, or invasion by an
evil spirit, of which traces still remain in such expressions as, "She
was _seized_ with a convulsion," "He was strong enough to _throw off_
the illness," "He was _attacked_ by a fever," etc. But apart entirely
from such conceptions, which were perfectly natural in the infancy of
the race, while clearly recognizing that disease is simply a perverted
state of nutrition or well-being in the body of the patient, a
disturbance of balance, so to say, yet it is equally true that it has a
birth, an ancestry, a life-course, and a natural termination, or death.

This recognition of the natural causation and development of disease has
been one of the greatest triumphs, not merely of pathology, but of
intelligence and rationalism. It has done more to diminish that dread of
the unknown which hangs like a black pall of terror over the mind of the
savage and the semi-civilized mind than any other one advance. It
contributes enormously to our courage, our hopefulness, and our power of
protection in more ways than one: first of all, by revealing to us the
external cause of disease, usually some careless, dirty, or bad habit
on the part of an individual or of the community, and thus enabling us
to limit its spread and even exterminate it; secondly, by assuring us
that nearly all diseases, excepting a few of the most obstinate and
serious, have not only a definite beginning, but a definite end, are, in
fact, if left to themselves, self-limited, either by the exhaustion and
loss of virulence of their cause, or by the resisting power of the body.

All infectious diseases, and many others, tend to run a definite course
of so many days, or so many weeks, within certain limits, and at least
ninety per cent of them tend to terminate in recovery. It is a most
serious and fatal disease which has a death-rate of more than twenty per
cent. Typhoid, pneumonia, diphtheria, and yellow fever all fall below
this, smallpox barely reaches it, and only the bubonic plague, cholera,
and lockjaw rise habitually above it. The recognition of this fact has
enormously increased the ef