What do you think makes certain things "classic"? Like, why in your opinion do certain pieces of literature become important?Certain music become revolutionary? I think it has to do with the way society is at that time, or maybe it's a whole lot of luck.
Standing the test of time without losing any of the oomf that made you so good in the first place makes you a classic. It's hard to say, my classics aren't somebody else's classics. Why is Guns N Roses "classic rock" now? Why do some of the so-called "classic" albums suck? Some things just strike chords in people and set off repercussions that change the way things are, and those things become classics. When you touch people, you're a classic. Unless those people are underage, then you're a predator.