The essence of doctors' duty is to bring three things to their suffering patients: knowledge, to discover what is wrong and what to do about it; compassion, to keep their patients' needs ahead of all other considerations; and the tenacity to persist in their work of healing, whatever may block the road.

Using case illustrations from his own and colleagues' experiences, Dr. Richard Hudgens, the senior clinical psychiatrist at the Washington University School of Medicine in St. Louis, shows how these principles are applied in 21st century psychiatry.

He provides a yardstick by which the...