What makes a novel "a classic"?

A novel is a classic when it is often referenced and seen in other medias of art or expression. Often, classics are made into films or referenced in modern-day medias. A novel is classic when it is remembered and referred to. If a novel makes an impact in society during the time it was written, then that also makes it a classic. Furthermore, if it changes the societal view or structure of the time, it is classic. Any novel that makes an impact, enough so that it is referenced in the future, time & time again, then it is a classic. If people of all generations are familiar with the novel, then it is classsssic.