From "Mysteries of The Unknown"

Do the dead watch over the living? Do they, at crucial times, intervene on our behalf? If not, then why do so many claim to feel the quiet presence of a deceased friend or loved one at crucial times?

Eminent 18th Century nerve specialist, Doctor S. Weir Mitchell, fell asleep in the sitting room of his Philadelphia home one winter evening after a long day of surgery. Awakened by the doorbell, he found a frail, shivering girl on the doorstep, pulling a ragged shawl about her shoulders. She begged him to come and treat her mother who was gravely ill.

The doctor followed her through the wintry streets to an old tenement. There, the doctor found the sick woman -- a former servant of his household. He diagnosed her condition as pneumonia and sent for the appropriate medication.

After making the woman as comfortable as possible, he commented on her dutiful daughter. The old woman looked shocked. "My daughter died a month ago. Her shoes and shawl are in that little cupboard." The doctor looked and found the shawl which had been draped over the shoulders of the girl who rang his doorbell. It was folded and dry, and could not possibly have been worn outside that night.

Explanation: UNKNOWN