History teaches us that civilizations flourish, die and disappear. Sometimes they died swiftly, sometimes in a slow lingering death. And sometimes, as with Rome and others, echoes of that civilization find new life in later cultures. To lose the conscious memory of an entire civilization is especially tragic and dangerous, because each civilization, no matter how grand or flawed, is a laboratory of human ideas and ideals, of dreams and nightmares. We can learn from all of them.