Gottfried Keller (July 19, 1819 to July 16, 1890) was a Swiss writer who achieved fame for the stories he wrote in German. Sources vary about his date of death, but Britannica has July 16, 1890. One of his stories is "Spiegel das Kätzchen." This is literally, "Mirror the Kitten," but it translated into English as "The Fat of the Cat." This widely anthologized story does not seem to be in the books I have, but here is an illustration for the story that Eileen Mayo did --
Doesn't help much in terms of story content, but at least we know we want to find a good translation of Keller's "The Fat of the Cat", OR, learn German.