They believed that a genius was this, sort of magical divine entity, who was believed to literally live in the walls of an artist's studio, kind of like Dobby the house elf, and who would come out and sort of invisibly assist the artist with their work and would shape the outcome of that work.
De troede, at et geni var en slags magisk guddommelig enhed, som boede i væggene i en kunstners bolig, lige som husalfen Dobby, og som ville komme ud og usynligt assistere kunstneren i sit arbejde og hjælpe med at forme resultatet af arbejdet.