One of the books I loved as a child. It differs from most other books by Kästner I've read (The Emil stories, The flying classroom) - a bizarre, funny story. Maybe books like this (and the works of Michael Ende of course) were the reason for me to pick up fantasy literature as a teen.
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In 1931, Erich Kästner probably had good reason to think that the world that adults were making for themselves was far from perfect. It's not for nothing that this comic fantasy adventure features a ludicrously suburban Valhalla where deceased generals of the past play with tin soldiers among the rose bushes, a roller-skating circus horse made redundant by mechanisation, a school where Difficult Parents are punished for their cruelty and neglect, or a futuristic city where a giant, automated, Upton-Sinclairish slaughterhouse suddenly starts running in reverse and spewing out confused cattle into the streets. There's plenty here that was meant to give offence to adults, but nothing that won't entertain and amuse any child. (Although some modern children might find things like moving sidewalks and pocket telephones with voice-dialling a bit silly!)

Fans of C.S. Lewis should take note that Kästner was way ahead of him with the wardrobe trick! ( )