It is said that at the end of the 19th century, a mysterious young woman drowned in Paris in the Seine. Though her body was put on display, as was the custom then, no one could identify her.

Yet her presence attracted many gawkers and much romantic speculation. People suggested she threw herself in the river because of a broken heart. The story goes that the morgue director was so enamored with her visage that he had a mold of her face made. Eventually, copies of this death mask would be sold by the millions throughout Europe. It was transfixing. The girl’s expression was, all at once, innocent, beguiling, and knowing. And oddly peaceful.

L’inconnue de la Seine, or the Unknown Woman of the Seine, has inspired poets and novelists alike.

Yet forensics experts have wondered aloud if it is possible that the mask could have been made from a drowning victim—such corpses tend to have bloated, or worse, skin.

Ironically, the “death mask” would go on to save many lives.

In 1960, after Pitt’s Peter Safar codeveloped cardiopulmonary resuscitation (CPR), he called Norwegian toy maker Asmund Laerdal. Would he be willing to create a mannequin on which people could practice CPR? Laerdal, as it turned out, had just saved his 2-year-old son from drowning. He consented and suggested the mannequin bear the face of the unknown drowned girl; his family had one of the masks.

The girl now has a name—Resusci Anne. And each year, more than 12 million CPR trainees attempt to breathe life into her.