They used to dream that they could escape the bonds placed upon them, that someday they would once again live freely. As time went on that dream died out and the dream of seeing another day and another after that is all that mattered. The dream, the only hope was that they would simply survive.
Even then when survival was all that mattered to them, the dream of a free life remained, not for themselves but for a future generation. If they could fulfill their own dreams of survival then perhaps their children would be able to dream of more.