None was sufficient alone.

Together, they produced an outcome that should not have been possible but was — an outcome that medicine has spent forty years studying and incorporating into the principles that guide the treatment of people who nearly die from cold.

Jean Hilliard froze on a porch step in Lengby, Minnesota, in December 1980.

She was talking by noon the following day.

The mystery of how that happened is largely resolved — the framework is clear, the mechanisms are understood in general terms, the limits of what is recoverable have been extended by subsequent research to include even more extreme cases.

What remains, after all the resolution, is the simple fact of it: a body so cold it looked dead came back.