One of the popular hypotheses of the origin of the bubonic plague is reminiscent of a children's philosophical fairy tale, the analogues of which are in doubt in Russia. Which became the reason for me to write about this. The hypothesis is that the plague occurred due to the belief that black cats are the devil's pets. The fairy tale describes what came of it, and is presented in a form accessible to children’s understanding. Published in the author’s edition, preserving the author’s spelling and punctuation.