Which sentence express the main idea of this paragraph?

1Over forty years ago, a doctor at the Mayo Clinic wrote that four out of five times he'd find out what was wrong sooner if he started by examining the patient's home life, his job, and his bank account instead of his heart, his digestive system, and his kidneys. 2 Many of his colleagues thought he was crazy or was at least playing a joke on them. 3 He was neither crazy nor was he playing a joke.4He had come to understand what few doctors at that time did: that bodily functions are affected by spiritual and emotional phenomena as well as by physical influences.