Writing one good sentence… you sort of need to have something to write, good or bad.
But that may not be the best approach.
The best approach may be to first feel around the cracks in the wall until you can find the one that’s a door. Then, pry open the door — just enough to slip inside the dream world. Like finding a passage inside a pyramid: there are mysteries we cannot get away from because we know this is not just an ancient pile of rock, but a psychotic (to us) universe that is built into the structure (in addition to the art, writing, corpses placed inside.) You just want to know — what is in there, of someone else’s experiences, fantasies, soul?
Just say what you find.