Pain: The science and culture of why we hurt
The full quote/excerpt
“There are psychic factors involved in every patient’s complaint of pain,” [Bill Livingston] wrote. He tells a story of one midnight emergency to illustrate his point.
A woman called him to report that her husband had just had a “massive bowl hemorrhage and was in a state of collapse.” Just before bed, he had felt some cramping pains and hurried to the bathroom. Then she heard him calling her name, followed by the thud of him falling to the floor. She found him unconscious, white-faced, and covered in sweat. And in the toilet there was a quantity of bright red blood.
Livingston told her not to flush the toilet and rushed over. He found the man lying on the bed, conscious, but in pain. Where does it hurt the worst, Livingston asked. “All over,” the man whispered. He went on groaning as his wife said that he had been in fine spirits and good health, until he had gone to the bathroom.
Livingston examined him, to no avail. Then he went into the bathroom and inspected the alarming-looking contents of the toilet. Beets. Lots of beet fragments. It turned out that her husband had eaten beets for lunch, and little else. Livingston decided that this accounted for the “hemorrhage” and that the man’s state — the pallor, the sweating, and the “all over” pain — had been entirely caused by fright.
The two of them walked back into the bedroom with smiles on their faces, which annoyed the husband, who was languishing on the bed. But when Livingston gave him his diagnosis, the man’s condition improved rapidly. “Within half an hour he was moving about in his usual energetic fashion and offering to pour me a drink if I would stay and chat.”

Comments and context
This is an amazing anecdote about the power of perception!