Quite a few of my dreams seem to be slightly scary situations (dangerous behavior of other drivers while I'm driving, for example). This makes me think that we

Quite a few of my dreams seem to be slightly scary situations (dangerous behavior of other drivers while I'm driving, for example). This makes me think that we have a "scenario generation" engine as part of our brains, and so we're being presented with novel experiences (often "wild and unrealistic") to react to. So this seems to be a pretty big step beyond the idea of presenting previously seen situations (which sounds like a really good first step, of course).