What Makes a Novel "a classic"?

A classic is a novel that has been discussed thoroughly, is controversial, contains complex literary devices, has a moral, and contains well developed themes that can be identified throughout the piece.

All great classics have some kind of controversial aspect to them that sparks discussion and arguments between literary analysts.  The controversies are usually the result of different interpretations or arguments over whether the novel is appropriate or insulting.

Another aspect is whether the novel uses literary devices, especially complex metaphors and visual descriptions.