probably exaggerate the extent of this instinctive knowledge);
and if this be true, man must have inherited from his prehuman
ancestors this instinct along with the others. That he extended
this knowledge through observation and practice, and came early
to make extensive use of drugs in the treatment of disease, is
placed beyond cavil through the observation of the various
existing barbaric tribes, nearly all of whom practice elaborate
systems of therapeutics. We shall have occasion to see that even
within historic times the particular therapeutic measures
employed were often crude, and, as we are accustomed to say,
unscientific; but even the crudest of them are really based upon
scientific principles, inasmuch as their application implies the
deduction of principles of action from previous observations.
Certain drugs are applied to appease certain symptoms of disease
because in the belief of the medicine-man such drugs have proved
beneficial in previous similar cases.

All this, however, implies an appreciation of the fact that man
is subject to "natural" diseases, and that if these diseases are
not combated, death may result. But it should be understood that
the earliest man probably had no such conception as this.
Throughout all the ages of early development, what we call
"natural" disease and "natural" death meant the onslaught of a
tangible enemy. A study of this question leads us to some very
curious inferences. The more we look into the matter the more the
thought forces itself home to us that the idea of natural death,
as we now conceive it, came to primitive man as a relatively late
scientific induction. This thought seems almost startling, so
axiomatic has the conception "man is mortal" come to appear. Yet
a study of the ideas of existing savages, combined with our