The scariest part of The Exorcist (1973) for me wasn’t all the bedroom acrobatics and green puke, it was a much subtler scene. In it, Father Karras sits before large spinning reels as they playback the recorded voice of possessed 12-year-old Reagan MacNeil, all of it incomprehensible gurgled groans and anguished, hoarse throatiness. Karras wants to know what language it is and the guy who’s assisting him has the answer: “It’s a language alright.” He pauses. “It’s English.” Turns out Reagan was speaking English in reverse. It then cuts to Karras later that night, lit by the low light of…