Michael Ende published Momo in 1973. In the book, the grey men, die grauen Herren, are a gang of time thieves. They pose as a Zeitsparkasse, a time savings bank, and persuade people to save time. Momo’s friend Beppo, the street sweeper, is the older, slower and calmer of her two closest friends. He explains to her how he sweeps a very long street: Man muß nur an den nächsten Schritt denken, an den nächsten Atemzug, an den nächsten Besenstrich. You only have to think of the next step, the next breath, the next stroke of the broom. The publisher Thienemann offers teaching materials for the book and recommends it for grades 5 to 8.