The event the story is based on, is when in the city of Székesfehérvár passing by the playground in Zichy liget, with my dear relatives we have became aware that one of the swings was swinging at such a long arc as if someone was driving it, while at the playground the headcount was zero, and during our approach towards we have seen no-one who had left from there, so at least minutes have passed since anyone had used it. We stopped and watched it moving uniformly, without slowing down, and there was hardly any wind that could have possibly driven it. We were waiting for long, but the swing was just swinging steadily.