villakoiran ydin

Etymology
, ; from the play Faust I by Goethe, in which Mephistopheles (the Devil) appears to Faust in the shape of a black poodle. When Faust learns the truth, he comments: ; translated into English in the play as "So this, then, was the kernel of the brute!").

Noun

 * 1)  core of the issue, essence, trick, catch inherent nature of an idea, especially one that is not apparent