Edith Davis was an early pioneer in the spread of acupuncture in the midwest. She was a very demanding teacher who insisted that the medicine and diagnosis took precedent over medical techniques. She was adamant that there needed to be a true understanding of a problem before treatment was considered. One of the analogies she often used, was that a proper diagnosis was like making a stool. You needed to have at least three legs for it to stand up and function as a stool.
The three legged stool concept is important when looking at a complicated system like the human body. Symptoms are interrelated and often the body has a limited vocabulary when it comes to expressing what is going on. There are numerous situations that can cause a red rash on the skin. If a treatment is based on just the one symptom of the red rash, it is likely to fail. There needs to be other supporting signs and symptoms that clarify why there is a rash. Only when there are at least two other supportive symptoms to clarify a diagnosis can a treatment stand on its own and be reliably effective.
The advise is something that all medical practitioners and patients should heed. It is very easy to get caught up in looking for one specific symptom and then basing a medical treatment on that one symptom. It is easy to become misled by one symptom which may have in fact many possible causes. The marketing of various cure-alls often relies on patients not taking the time to match a treatment to enough supporting information. The best application of medicine is based in knowledge and understanding, not the latest latest and greatest technique used without a supporting diagnosis.