pudelns kärna

Calque of German des Pudels Kern (literally “the poodle's core”). The phrase is taken from a scene in Faust, Part One during which a black poodle follows Faust home and transforms into a wandering scholar, who is actually Mephistopheles in disguise. Faust exclaims: "Das war also des Pudels Kern!" (“So that was the poodle's core!”); that is, "So that's what was going on inside the poodle!".

pudelns kärna c

1. the crux of the matter, the gist of the matter, the heart of the matter

   Pudelns kärna är om behandlingen gör honom lyckligare

   The heart of the matter is whether the treatment makes him happier