"Yeah, we wouldn't even have tried until we thought we could pull it off across the whole planet at once, so it can't have been any earlier than that, in our history... I wish I knew whether dath ilan went through a phase like that, or if it's something that happens here entirely because of the gods or a leak in your heritage of intelligence or I don't know what. If dath ilan used to look basically like this, minus the gods and magic, it sure would be nice to know exactly how we climbed out of it."
For the first time it occurs to Keltham to wonder if dath ilan used to have gods, and that's what the Great Screen is meant to protect, because if you know the info for gods, you might pray to them... it would take a huge effort to keep not just the phenomenon but the physics behind it out of all the textbooks, but that's the magnitude of effort dath ilan put in to the Great Screen. And if that's not what's going on, then there remains the unexplained question of why Keltham does not know any standard theories about hypothetical superagents, that lots and lots of people could have hypothesized, hypotheses which pose a lot of interesting then-whats once you start looking in that direction.