Physicians later divided themselves into doctors who are interested in diseases of the lungs, and other doctors were interested in diseases of the skin. Other doctors were perhaps interested in disease of the intestinal tract or the reproductive tract or the urinary tract. The medical community organized itself that way because that was the level of sophistication at the time. But starting with Louis Pasteur about a hundred years ago, a change occurred. And when we speak of why disease occurs, we speak of something else, and that is what we call etiology.
Etiology means cause.
If we are concerned with curing disease and possibly even preventing disease, the etiology is extremely important information. Because we now know the bacteria and the viruses and the parasites that cause these diseases, and we can develop antibiotics and other drugs that will specifically attack that organism. Discovering the etiology has allowed medicine to progress to its present state where we can successfully treat and even cure many diseases. Within the lifetime of most of us, we have ways of effectively treating infectious disease. Until World War II, until antibiotics were introduced, we did not have methods that cured disease.