Paul Virilio: There is a French expression that says: to be exposed to an accident, to cross a street without looking at the cars means exposing oneself to be run over. This is more than a play with words, it's fundamental. For instance, when a painter exhibits his work, one says: he exposes his work. Similarly, when we cross the street, we expose ourselves to a car accident.
Works of art (if they're any good) are like exposures. They are a look inside at the thought processes of the artist. When an artist exposes work in a public display, then it is like pornography. The public at large is allowed an intimate peek at the insides of the artist. Sometimes people are just titillated by this peek or maybe it resonates with the insides of the viewer and so the viewer will be affected. If this happens to a large number of viewers, then the art grows popular. Art may also incite fear or anger as it threatens to reveal the insides of the viewers. Everyone carries with them their own pornography.