And, of course, the immediate effect is that Altarrin notices several ways in which he's been reasoning stupidly.
(This spell by itself continues to be - actually pretty unpleasant to experience - but on its own, he suspects it would feel less like waking-up-after-dying than it did when combined with the headband. And he doesn't think he needs the working memory boost as badly; for one, he's caught up on sleep now. And it might matter that he can bounce ideas off Carissa, who has substantial context on dath ilan that she hasn't conveyed to him yet, even if she too is seeing it at a remove.)
There isn't an obvious answer, is the first thing he notices. He just doesn't know enough; he's making inferences based on shadows cast on a wall and then reflected across a hazy mirror, and anything he can come up with is fundamentally a guess, filtered through his own priors and understanding of the world.
But, even taking that into account -
- what is dath ilan trying to achieve?
The same way that the Empire tries to teach all of its schoolchildren to read and write, dath ilan tries to teach all of its schoolchildren to - what. To use the decision theory gods use, is how Carissa put it. To shape themselves and their minds such that their precommitments would show up in Foresight, legible to the gods. A way of thinking about one's own decision-process that Altarrin recognized, and Carissa didn't disagree with his assessment.
(And they their children into cohorts, which might or might not matter, it seems self-evident to Altarrin just in terms of good pedagogy, but Carissa brought it up specifically, and he suspects it wasn't self-evident to Cheliax– side point, he can worry about it later.)
When a young dath ilani winds up in Cheliax, and the authorities order their best and brightest to learn from him, this results in more heresies than most projects would tolerate. Up to and including a student of Keltham's deciding to defect and personally oppose the god they once served. And Altarrin suspects Carissa isn't saying everything.
Corollary: the Eastern Empire, for all that he wants to argue that it's a better place to live than a country under the dominion of the god of Hell, is similar in enough ways. It would destabilize things, if you tried to run a single important project that taught its members these reasoning techniques, let alone if you taught them to all schoolchildren everywhere -
- but dath ilan isn't unstable. Dath ilan is tidy and organized, prosperous and technologically advanced beyond what he could have imagined possible before now.
They taught them all to question society but they all ended up at the same answers, is what Carissa said.
There are a lot of possible explanations, including that dath ilani natives only look human but have fundamentally different minds, but, but even holding that in mind -
- it feels like a civilization that was skillfully built to be a certain way on purpose.
What purpose.
Well, if everyone is taught to reason - the way that gods do, (that's not quite right but he's going to keep using it as a mental shorthand for now), they're going to notice discrepancies, you couldn't run a stable Empire off propaganda and incentives to lie, but at the same time your people are more legible and more predictable -