Phineas Gage was a young up-and-comer. He worked as a foreman for Rutland and Burland, a railroad-construction firm. He was smart, he had a head for business, and he was well-liked by his superiors. In 1848, when Gage was just 24 years old, he was overseeing the tamping of black powder into a small blasting site. He tamped just a bit too hard, hitting a buried piece of steel, and the resulting spark set off the powder. The tamping rod, 1 1/2 centimetres in diameter and a meter long, passed through the lower portion of his jaw, through the left side of the frontal lobe, and out the top of his head.

Gage did not die. He didn't even lose consciousness. He sat down, stunned, with a massive hole in his head. The exit wound was pushed outward dramatically and leaking blood, so that it resembled a sudden eruption of a volcano. He was helped to a local house where he waited, awake, totally lucid, for a doctor. The doctor, John Harlow, came and did what he could, fighting off the inevitable infection. An infection on a wound of this magnitude should have been enough to put down Paul Bunyan. Gage somehow came through it. As the good doctor later said, 'I dressed the wound, God healed it.'

But Gage was changed. He seemed to have regressed in many areas of his personality. He was suddenly coarse. He spent money like water. He had the attention span of gravel. He could not hold a job or support himself. This formerly bright young thing was reduced, in an instant, into a foulmouthed braggart of a failure - a child in a man's body, almost. He was (reluctantly) thrown out of his job at Rutland and Burland after many demotions. He tried many jobs, clerking, farming, never putting in enough work to succeed. It was said that, after jobs driving coaches and working the stables, he joined a traveling freakshow. He eventually died thirteen years later, penniless.

This case was the first evidence that different parts of the brain had different functions. Various people took the case and ran with it. A leading professor of phrenology used the case as evidence towards the correctness of his science. Another doctor (from Harvard, no less) claimed that this showed the brain was totally disconnected from any sort of 'mind' (a popular idea of the previous two centuries, called something like dualism, IIRC) because his speaking and motor faculties were totally unaffected.

It does appear now that the wound did cut right through the right centers of his brain without affecting any speech or motor areas - someone preserved Gage's skull, so that the wound could be reconstructed later. Also, cases involving specific brain damage were later recorded showing lesser versions of what Gage went through. All of the cases shared certain commonalities, like the loss of control of impulses and the loss of attention span. Gage kept the tamping rod, showed it off to people, and used it as a walking stick - evidence of what scientists call 'collector's instinct', seen in many examples of brain damage.