Idea for a short story
A poet spots a man she doesn't know quietly leaning on the mantlepiece in the background of a literary salon, looking faintly superior. She starts seeing him at all the artistic gatherings she attends and assumes he's some brilliant, but reserved, genius. When she finally gets to meet him, she discovers that he is, in fact, spectacularly dim and knows nothing, his resting expression just looks very impressive. She and a bunch of her friends start publishing work under the leaning man's name and he quickly becomes famous for the breadth and variety of his work. His habit of answering any questions with 'I know nothing' is read as evidence of his deep wisdom. When the literary prank is revealed instead of shaming him, he is instead praised as a great satirist and japester and eventually ends up President, with his poet friends behind him as the unacknowledged legislators.