On the "Angels and Demons" ambigrams... The artist made such an impression to the book author, Dan Brown, that he (Brown) decided to name the protagonist after

On the "Angels and Demons" ambigrams... The artist made such an impression to the book author, Dan Brown, that he (Brown) decided to name the protagonist after him. Here's John Langdon, artist: https://www.johnlangdon.net/ https://www.johnlangdon.net/ Having met John (I showed him the second largest Escher collection), I can confirm he's a wonderful person.