Youth (Sci-Fi Classic). Isaac Asimov

      "With its atomic bombs?"

      "The atomic bombs," returned the Astronomer, "need not be the end of civilization. These visitors of mine had their atomic bomb, or whatever their equivalent was on their own worlds, and survived it, because they didn't give up. Don't you see? It wasn't the bomb that defeated us, but our own shell shock. This may be the last chance to reverse the process."