TIL the term “gaslighting” originates in a British play-turned film from the 1930s. The play was called “Gas Light” and the plot is about a husband who mentally and emotionally manipulates his wife...
"...into believing she is crazy by changing the intensity of the gas lamps within their home. He does other crazy-making things like knocking on the walls or moving/disappearing items around the house. This obviously brought up some questions from Paula, the grieving and rich wife he had quickly married after discovering she had wealth."