So then. Assuming that actual editorial discussion of Adventure 12 is satisfied, lets move on to the discussion of what it may mean for the setting.
As I suspected, I found some of the subtext clues I remembered:
"the true history of the ancients is best known to one Ancient the one who started the ancients civilization,, and who is miraculously still alive today.
The following is the story that he can relate" (p42)
Okay, not a smoking gun, Far from it. But....it doesn't say, "this is the true secret of the ancients"; it also makes a point that there is no way to verify this story. Interesting. It isn't presented in the context of the library data, or in the ex cathedra style of background data, but rather, "this is what you are told". Finally, it isn't even from Grandfather, who isn't even in the room for most of this.
Then after this speech, they get sent home, and the door is locked so GF won't be bothered.
So, the conundrum is this: if a genocidal utterly pragmatic god wants to be left alone, why doesn't he just kill them and close the portal ? What's three or four more more lives among the billions he has massacred ? Why isn;t his ship better safed against misuse, or bringing nosy-parker lesser beings to his doorstep; he is after all a "super genius" who is able to instantly recognises who they are and how they got there......really ?
If nothing else, even if he has had a sudden coversion to pacificsm and respect for all life, the power to erase memories exists in the imperium and the Zhodanis -heck, it almost exists tody- so why not release them with shiny clean memories of somthing else ? Or just keep them as pets ? Or just ask them to cross their hearts and promise not to tell ?
We know a few things -first, his robots are capable of deciding things and not bothering to consult him; second, he still interferes with the lesser races outside the pocket; third, he's still watching the droyne, and has at least enough affection for them to preserve a breeding population, and to allow them to rediscover civilization.
So.....the droyne needed something expunged from their culture -so thoroughly that it required near complete genocide or exile from the universe to hide it.
We have an indirect unverifiable story from one of GFs servitors (to be fair, probably from GF directly); and a glaring internal contradiction of a basic rule of coverups: -if you want to keep a secret, don't tell anyone, and if they fnind out....well, what kind of men tell no tales ? So why let it out ? Because it draws attention away from either the real story, or from something far more important; something important enough to squash billions of sentients to cover up; something that still is a big deal; and something that the current races may be approaching unless they get distracted.
So, The Secret of the Ancients is a stalking horse perhaps; or just disinformation intended to hopelessly muddy the waters of ancients research; or, he's meddling again, or is an agent of something that is shaping charted space and wants this "secret" known, as part of the project.
Actually, the more I look at the contextual stuff from the adventure, the more I wonder if it really wasn't intended to be definitive, rather than just a quick fix to a mystery. This is me though. I'm kind of gullible that way.
