“Until forty years ago, doctors possessed a few great remedies which they often used very skillfully, but the knowledge of the nature of disease was very slight. Treatment was largely symptomatic; that is, remedies were expected chiefly to combat certain symptoms, rather than to treat underlying causes. “A notion very prevalent until then, and which has not yet disappeared entirely, was that there is a remedy for every disease, and that whenever a patient is not cured of his illness it is due, not to the limitations of the healing art, but to the fact that treatment was not begun early enough, or his doctor didn’t know enough, or didn’t care enough to give him the right medicine. About that time it began to dawn on the most thoughtful and capable medical men that the course of disease can usually not be quickly checked; that most diseases run a definite course; that most patients recover spontaneously, or the disease persists to the end and is not much influenced by any of the remedies used. About that time medical men began to appreciate also another fact: that underlying most diseases, there is a natural tendency toward recovery, which means that most diseases will cure themselves if given time enough. “While medical men insist that the practice of medicine is both a science and an art, they are also perfectly willing to admit that it is neither an exact science nor a perfect art. In other words, modern medicine admits that it has not yet scaled the heights or fathomed the depths of scientific knowledge in regard to the nature of disease or of its cure. It is still willing to learn. Indeed, it realizes the fact that there is still infinitely more to learn than has yet been found out. And there is no avenue of human knowledge which it is not willing to explore in order to find out things that will get the sick well and keep the well from getting sick. “A stunning blow to the old notions of the nature of disease and to the old methods of treatment, was administered about thirty years ago by the discovery that most diseases are due to infinitely small, living organisms, called germs or bacteria, which prey upon, or poison the tissues of the body, and thereby disturb, more or less seriously, some, or all, of the normal functions of the body. The scientific laboratory thereupon became the shrine of modern medicine; a new epoch in medicine had arrived.