In the 18th century there was pain and misery, but art generally displayed the beauty of the world. In the 19th century there was also pain and misery and art showed a part of it. In the 20th century there was a lot of pain and a lot of misery and very often art became unpleasant because the artist felt the need to show the world all the unnecessary pain, the avoidable misery, the great alienation and violence that govern human relationships. For many artists, failing to do this would have...