There is one passage in _Mark Twain's Notebooks & Journals_ that
also offers a glimpse of Twain's views on the topic when he
compares the standards for art vs. literature:

Criticism is a queer thing. If I print "She was stark naked" - & then
proceeded to describe her person in detail, what critic would not
howl? - who would venture to leave the book on a parlor table. - but
the artist does this & all ages gather around & look & talk & point. I
can't say, "They cut his head off, or stabbed him, &c" describe the
blood & the agony in his face.
- Notebook #18, Feb. - Sept. 1879

Barb