Percy Shelley doodling while helping his wife edit the draft of her first novel, Frankenstein; or, The Modern Prometheus (1818):
The idea for the story was devised in mid-June 1816. The draft shown here was written between August and December 1816, and it was revised until April 1817. The book was published January 1st 1818 when Mary was 20-years-old. She was only 18 when she conceived the story, as her 19th birthday was on August 30th 1816.