A permanent winter had fallen upon the world, feet of snow insulating the ground, falling, always falling. Whether because of the extreme winter, or some other disaster, people had begun retreating to underground caves and living there, with some of the old comforts. Hoarding artifacts of the past in the hopes that someday someone would find them. The caves were warm and not so different from our old homes. We had stoves and light, furniture. More like cozy, underground hobbit house than caves.
I am standing in front of a deep stone wall of the cave in which we live. I run my hand over the carvings made by a friend now gone, who had themselves studied the ancient cave paintings. (Who this friend was and what happened to them, I can't quite grasp.) These carvings were done "before" in the hopes of creating a lasting record of our myths and history. The fear being that it would be so long into our future before people again had the luxury to study the past instead of just surviving the future, that only the stone would be sure to survive.
We have an entrance on each end of the cave, tunnels that climb up towards the cold. One entrance collapses. We try to dig it out, to squeeze out towards the light, but it is solid and we are left with only one way out to the world. And this is only the beginning. Other caves begin to collapse, leaving people trapped and dying underground. And the decision is made, for everyone to move out of the caves, away from the last remnants of comfort and technology, of our lost civilization. And we leave the artifacts of our past behind. The books and music and carving on the cave walls. Leave them behind in the hopes that someday people will find the things we left behind and learn of what was in the "before." And out we go, into the new cold world and try to survive in the new winter.