Full Idea
No artist has ethical sympathies. An ethical sympathy in an artist is an unpardonable mannerism of style.
Gist of Idea
Having ethical sympathies is a bad mannerism of style in an artist
Source
Oscar Wilde (Preface to 'Dorian Gray' [1891])
Book Reference
Wilde,Oscar: 'The Picture of Dorian Gray' [Penguin 1949], p.5
A Reaction
This has a Nietzschean suggestion that the artist is 'beyond good and evil', and operates on some higher level of values, which in Wilde's case seem to be purely aesthetic. You can't justify a callous murder by executing it beautifully.