"He who controls the past controls the future. He who controls the present controls the past."
My definition of a truly classic novel is one that is so talked about and referenced that you can know all about the book and it's message without having ever actually read it. 1984 is one of the most glaring examples of this, as terms such as "Big Brother" and "Doublespeak" are now mainstream concepts that no longer require explanation.
The book itself gained its popularity, however, by successfully reaching a broad audience through exaggerating and reducing the complicated debate of the illusion of free will and freedom of thought in any kind of government structure that strives to control and manipulate the populace for its own benefit in an almost unbelievable science fiction setting. The extremes that are reached in 1984 may seem only possible in a work of fiction (or, as the work is seldom referred to these days, Science Fiction), yet there is a truth beneath the pulp novel trappings that most readers can not avoid recognizing.
For those who have already read this, I have a suggestion. Read 1984 again, only assume that the book actually takes place in our modern times, and that the narrator is a paranoid schizophrenic.