Question: What Makes a Masterpiece?

“A masterpiece isn’t a masterpiece until it is well known and has absorbed all the interpretations to which it has given rise, which in turn make it what it is.  An unknown masterpiece hasn’t had enough readers, or readings, or interpretations…A work of art isn’t created a masterpiece, it becomes one…the authority, the familiarity and the relevance of a great work of literature: we open it, and it speaks to us of ourselves…naturally every reading affects the book, in the same way as the events we experience effect us…”

Umberto Eco & Jean-Claude Carriere, This is Not the End of the Book

Your thoughts…?  Any “unknown” masterpieces possible?