If string theory succeeds, its success will represent the culmination of the idea that we understand the universe best when we consider it on many scales. During the last hundred years in particular, the collective effort of numerous physicists has revealed some of nature's best-kept secrets. And once revealed, these explanatory gems have opened vistas on a world we thought we knew, but whose splendor we had not even come close to imagining. We do not know. After all, no one yet understands completely what string theory is, and the tools needed to extract its predictions are still being developed.
String theory is a beautiful dream, beautifully told in The Elegant Universe .