"In 1919, Charlie Chaplin had an idea for some fleas. Wouldn't it be good, he thought, if a man accidentally opened his matchbox of performing fleas in a dosshouse? But he could find no place for the scene in the film he was shooting. He tinkered with the idea for almost a decade - wouldn't it be good if he inspected one of the fleas from a hobo's beard, only to throw it away because it wasn't one of his? - and almost got it into The Circus in 1928, and then The Great Dictator in 1940, but still it wouldn't fit. Finally, in 1952, with the communist witch-hunt closing in on him, the press baying for his blood, Chaplin made his last film on American soil, Limelight, about a washed-up clown called Calvero plying himself with greasepaint for one final hurrah. In a flashback sequence, we see Calvero finally lose those performing fleas, but not the whole box: just two of them now, hopping invisibly from fist to fist."
— From my review of Chaplin: The Tramp's Odyssey in tomorrow's Sunday Times