How did ancient Chinese judge the level of a doctor's in TCM?

The following words are the standards for judging the level of a doctor's  in traditional Chinese medicine (TCM) in China for centuries. They are still applicable to doctors of TCM nowadays.

"Superior Doctors Prevent Disease.

Mediocre Doctors Treat Impending Disease.

Inferior Doctors Treat Actual Disease."

There are different ways of preventing and treating various conditions in TCM. Taiji (Tai Chi), Qigong (Chi Kung), Chinese herbal medicine and moxibustion can be used for both preventing diseases and helping / treating / curing diseases.