When I was a kid, my parents had a book of famous paintings. One day, I turned the page and discovered a painting that absolutely terrified me -- I mean, nightmares for years and years. I had no clue who the painter was, and never saw the painting again. Then tonight, I was watching the movie IN BRUGES (great film by the way) and there it was: The Garden of Earthly Delights by Hieronymus Bosch. And if you'd assume that age would somehow dull my reaction to his work, nope. Still absolutely terrifying. In particular, I remember the "Tree-Man" of the right panel with the hollowed out cavity in his torso.
It's not a bad thing to be disturbed by art. Clearly, this painting made an impact. And as a writer, if I were to ever depict hell or suffering in some fantastical sense, I'd probably pull from Bosch.
However, now, I need to see some Norman Rockwall paintings to clear my head of the freakin' Tree Man. Rockwall is the Bosch antidote. They won't teach you that in art class, but you know it's true.