In 150 words, explain existentialism and quote text from "Hope, Despair, and Memory" that demonstrates or explains it.

Without memory, our existence would be barren and opaque, like a prison cell into which no light penetrates; like a tomb which rejects the living. If anything can, it is memory that will save humanity. For me, hope without memory is like memory without hope ...

Stripped of possessions, all human ties severed, the prisoners found themselves in a social and cultural void. "Forget," they were told. "Forget where you came from; forget who you were. Only the present matters." Night after night, seemingly endless processions vanished into the flames, lighting up the sky. Fear dominated the universe.

Indeed this was another universe; the very laws of nature had been transformed. Children looked like old men, old men whimpered like children. Men and women from every corner of Europe were suddenly reduced to nameless and faceless creatures desperate for the same ration of bread or soup, dreading the same end. Even their silence was the same for it resounded with the memory of those who were gone. Life in this accursed universe was so distorted, so unnatural that a new species had evolved. Waking among the dead, one wondered if one were still alive ...

Of course, we could try to forget the past. Why not? Is it not natural for a human being to repress what causes him pain, what causes him shame? Like the body, memory protects its wounds. When day breaks after a sleepless night, one's ghosts must withdraw; the dead are ordered back to their graves. But for the first time in history, we could not bury our dead. We bear their graves within ourselves.

For us, forgetting was never an option. Remembering is a noble and necessary act. The call of memory, the call to memory, reaches us from the very dawn of history. No commandment figures so frequently, so insistently, in the Bible. It is incumbent upon us to remember the good we have received, and the evil we have suffered.