Grissom: The bellows.
Hodges: I'm sorry?
Grissom: James Tilly Mathews. Early 19th century London. Mathews was in Bedlam hospital awaiting trial. Doctors were trying to determine his sanity. Several interviewed him. Half thought he was sane, half insane. Turns out he was perfectly normal, except when someone mentioned politics. At that point, he'd go into a rage about the little men who lived underground and used a bellows to push thoughts into his mind, as well as the minds of Parliament, and the Queen. A specific object or word triggers the urge to kill. That's a form of delusional psychosis. Rare, but it does exist.