Phineas Gage was a likeable railroad worker, aged 25, when an accident changed his life and medical science forever. He had an "iron frame" and an "iron will" to match, and was almost never sick or disagreeable.
But an explosion while working the railroad, according to his doctor John Harlow, "projected the iron obliquely upwards...passing completely through his head, and high into the air, falling to the ground several rods behind him, where it was afterwards picked up by his men, smeared with blood and brain." The "iron" was a tamping rod three feet and seven inches in length, with a diameter of one inch and a weight of 13 pounds. It went directly through his brain from the bottom and left through the top of his skull.
Phineas Gage survived for 12 years after his accident, but the injury to his brain changed his personality. He became disagreeable and unreliable. He lied constantly. Medical science began to realize that changes to the brain can affect personality.
His skull and the iron rod, which Phineas loved to carry with him after the accident, are now in the Museum of the Medical Department of Harvard University.