Coupled with this knowledge of things dangerous to the human system, there must have grown up, at a very early day, a belief in the remedial character of various vegetables as agents to combat disease. Here, of course, was a rudimentary therapeutics, a crude principle of an empirical art of medicine. As just suggested, the lower order of animals have an instinctive knowledge that enables them to seek out remedial herbs (though we 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 knowledge of the point of view from which historical peoples regard disease, make it more probable that the primitive conception of human life did not include the idea of necessary death. We are told that the Australian savage who falls from a tree and breaks his neck is not regarded as having met a natural death, but as having been the victim of the magical practices of the "medicine-man" of some neighboring tribe. Similarly, we shall find that the Egyptian and the Babylonian of the early historical period conceived illness as being almost invariably the result of the machinations of an enemy. One need but recall the superstitious observances of the Middle Ages, and the yet more recent