When I was growing up my father told me a parable of three brothers, all of whom had grown to be doctors.

One brother was a miraculous curer of all injuries and ills. It did not matter how far a disease or injury had progressed, he could cure the patient. He was known throughout the continent.

One brother was exemplar diagnostician of all injuries and ills. It did not matter what was wrong, he could diagnose the problem and if he was unable to solve the problem he would make a personal introduction the most knowledgeable expert on the matter. He was known throughout the country.

The third brother was just a humble backcountry physician. He wasn't very good at diagnosing or curing diseases. But he visited his clients frequently, and gave them advice on their diet, and home and work conditions. On the rare occasion when his clients got ill or injured, he tended them back to health and when possible helped them to remove the conditions leading to the ill or injury. He was only known throughout the village.