The world will still be here long after we are gone. Hopefully to other, better places. But as civilizations go and new ones rise, a lot of what was once good, in their culture, art, literature, gets forever lost. Most of the culture, art and literature of the Greeks and Romans was lost when their civilizations collapsed. And let us not forget, a new civilization rising over the old one is not a peaceful kumbaya process. It is violent, it is destructive, and it often replaces or subjugates the people that lived in the old civilization. It is not something you wish to experience and to those who did got to experience it it was the end of the world to them.