PHILADELPHIA — More than 40 years after losing his right arm in the Civil War, Henry S. Huidekoper, a lieutenant colonel in the Union Army, had long since adjusted, and no longer found himself trying to reach for things or write with his missing hand.

But somewhere in mind or memory, he was still whole. In 1906, he wrote in a letter, “In my dreams, I always have the use of both my hands.”

He dreamed of himself as “a man with a perfect frame” whose struggle to write with the absent hand sometimes sparked phantom-limb pains that woke him in the night.

The letter is part of “Broken Bodies, Suffering Spirits,” a permanent exhibition on Civil War medicine that opened here last fall at the Mütter Museum.