…e so vividly saw in the belly of a black machine, was stored within the deep recesses of her brain. And there too it stores the smells of apple pie, the taste of lips, the agony of unrequited love, the sounds of snow landing on snow, and the fear of dark alleyways.
Mark C Watney
And dreams can be "lucid."
Just today, I was talking with a friend who mentioned a famous politician she had once met. Suddenly, I was flooded with a FULL MEMORY of meeting an important person in a Presidential Administration, but suddenly realized it was the memory of a dream!
There was another person I had ACTUALLY met, but the dream "important official" didn't quite have a name because, well, he never actually existed.
We don't notice the little tip-offs when we're IN a dream, but we can train ourselves to do so.