What makes a novel "a classic"?

I've never really thought about what the actual definition of "classic" is. I guess it's something that has great value and is recognized as a perfect example of something. I think a novel becomes a classic when, first of all, it needs to have a pretty deep meaning behind its words. It should have a lasting effect on the reader, either a positive or negative effect. the novel should cause some type of controversy among it's audience. It should be an original story, something that has never been thought of before. It can be criticized, degraded, but it can never lose its value in the eyes of it's supporters.