Probably the last man who knew how it worked had been tortured to death years before. Or as soon as it was installed. Killing the creator was a traditional method of patent protection.

Pratchett jokes that lost know-how comes from a grim habit. Whoever understood the machine supposedly died for it, so nobody left can explain it. Calling murder 'patent protection' is the dark humour, treating secrecy as a business practice.

Context reviewed 28 September 2026