A young man on the Mississippi dreamed that his little brother was dead, laid out in a metal coffin resting on two chairs, with a bouquet of white flowers on his chest and one red rose at its centre. Weeks later he walked into a room in Memphis and saw it, exactly, in front of him.

The dreamer was Samuel Clemens, twenty two years old, a cub pilot learning the river, and not yet anybody's idea of Mark Twain. He adored his younger brother Henry, and had got the boy a job on his own steamboat, the Pennsylvania, as a mud clerk. Sleeping at his sister's house in St. Louis, Sam dreamed he came into the sitting room and found a metal burial case laid across two chairs. In it was Henry, in a suit of Sam's own clothes, with a bouquet of white flowers on his chest, and at the centre of it a single crimson bloom. He woke certain it was real, and did not go back into that room until he had walked outside and worked out that it had been a dream. Then he came back in and told his sister the whole thing.

Weeks later, Sam quarrelled with the Pennsylvania's pilot and was put onto another boat. Henry stayed aboard. On the 13th of June 1858, a few miles below Memphis, the Pennsylvania's boilers exploded. Many died at once. Henry was badly scalded, was carried to Memphis with the other wounded, and died there eight days later, and Sam, who arrived to find him, never stopped believing that he had killed his brother by getting him the job.

In the makeshift morgue, the dead of the Pennsylvania lay in plain unpainted wooden coffins. All but one. The ladies of Memphis had been so moved by the handsome dying boy that they had raised a subscription and bought a metal case for him. Sam walked in and found his brother lying in it, resting on two chairs. He was standing there when an elderly woman came in and laid a bouquet on Henry's chest: white flowers, with one red rose at the centre. Be clear about the evidence: the explosion and the funeral are documented fact, but the dream itself first reaches print in the biography published two years after Twain died, from his own dictated words. He told it, again and again, until he was an old man. He never once claimed to understand it.

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