Like, okay. Everyone in history thought they were the ones who finally knew everything. In their Renaissance, right, they were positive they knew exactly how the universe worked. Til the next set of guys came along and proved they were missing like a hundred important things. And then that set of guys were sure they had it all down, til another set came along and showed them parts they were missing." He glances at Julia, checking if she's laughing at him, which she isn't, and if she's listening, which she is, completely. "So." he says, "it's pretty unlikely, mathematically, that we are living in the one single era that has everything figured out. Which means there's a decent possibility that the reason we can't explain how ghosts and stuff could exist is because we haven't figured it out yet, not because they don't. And it is pretty arrogant of us to think it definitely has to be the other way around.

The Secret Place