Forget fingerprints. Unless you're a detective, the face is the part of human anatomy that is most important to identity.
Many societies consider it so intimate that it must be veiled. Halloween is scary partly because it is masked.
Expressions such as "let's face it," "face value," "losing face" and "saving face" reveal how profoundly this feature is stitched into human personality.
"Our face is the window through which others see and come to know us," wrote three University of Louisville doctors who have proposed doing face transplants.
All of which makes facial disfigurement so devastating to personality. It can lead to depression and suicide. It can confine the deformed to lives as shut-ins, fearful of the finger-pointing and distress their appearance causes others.
It can even contort someone's psyche into a criminal state. Fiction gives us the Batman villain Two-Face. Reality gives us Bart Ross, who earlier this year shot himself after killing the husband and mother of a federal judge in Chicago. Ross was despondent over facial disfigurement from cancer treatment.
The depth of emotional scars caused by physical ones is one reason Joseph Locala, a psychiatrist at the Cleveland Clinic, agreed to be part of a team that hopes to do the world's first face transplant.
He doesn't view removing a "diseased" face as removing someone's identity.
"In a sense, you're regaining your identity" with a transplant, he said. "If you're unable to smile, you certainly have lost your identity a long time ago."