I am convinced by the evidence that we are a species with amnesia, we have forgotten something of great importance from our own past. When we come, we will realize for the first time that our civilization isn't the apex of creation, the pinnacle towards which everything has been building through all of geological time. Rather, it is part of an up-and-down flow, that is possible for a civilization to reach a very high level of advancement and be wiped out. This is something we have never really confronted and we need to confront it