The 500 Hats of Bartholomew Cubbins

The 500 Hats of Bartholomew Cubbins is a children's book, written and illustrated by Theodor Geisel under the pen name Dr. Seuss and published by Vanguard Press in 1938. Unlike the majority of Geisel's books, it is written in prose rather than rhyming and metered verse. Geisel, who was a collector of hats, got the idea for the story when he was on a commuter train from New York to New England, while sitting behind a businessman wearing a hat.