"Elder Race" falls in the subgenre of "any sufficiently advanced technology is indistinguishable from magic." And that's a genre that I like!
Lynesse Fourth Daughter, a princess from the realm of Lannesite, is on the cusp of adulthood, but a mysterious threat is plaguing the border realms. The petitioners who come to court can only describe it as demonic; it's not any form of creature they recognize. But to make matters worse, Lynesse's mother and older sisters don't take it seriously, they assume it's just villagers exaggerating a political threat.
She wasn't a child anymore, and her mother and her sisters and tutors and the snide majordomo took pains to remind her of it, until she had looked in the smudged bronze of the mirror one morning and known it was true. And that things like the glorious ballads of Astresse Regent and her sorcerer were becoming like the bright clothes she could barely fit into, where all her new clothes were severe and stateswomanlike and sombre.
I enjoyed this characterization because, even though I do not have a lot of firsthand experience with sorcerers or even being a princess, I relate to the pressure of feeling like I'm being told: "those stories you enjoyed as a kid? stupid and shallow, time to be a Real Adult now! Real Adults hate Narratives, only boring ambiguity for us!"
So, in one last burst of childhood adventurousness, Lynesse does the obvious thing that any hero of a ballad would; namely, go on a quest to the nearby tower to consult the ancient sorcerer, last of the Elders.
Unfortunately, the sorcerer, Nyr, even though he's intervened on Lannesite's behalf in the past, has no experience with demons. So their back-and-forth of their different perspectives on this world and what might be haunting it sets up the story.
Nyr's society is a lot more technologically advance than Lynesse's, but they haven't figured out a long-term treatment for depression or anxiety.
And I am absolutely intellectually able to agree, yes, all of this great crashing wave of negative feeling is not actually being caused by the things I am pinning it to. This is something generated by my biochemistry, grown in my basal brain and my liver and my gut and let loose to roam like a faceless beast about my body until it reaches my cognitive centres, which look around for that worry du jour and pin that mask on it. I know that, while I have real problems in the world, they are not causing the way I feel within myself, this crushing weight, these sudden attacks of clenching fear, the shakes, the wrenching vertiginous horror that doubles me over. These feelings are just recruiting allies of convenience from my rational mind, like a mob lifting up a momentary demagogue who may be discarded a moment later in favour of a better. Even in the grip of my feelings I can still acknowledge all this, and it doesn't help. Know thyself, the wise man wrote, and yet I know myself, none better, and the knowledge gives me no power.
Even though my symptoms aren't as severe as Nyr's, I think this is a great description of the relationship between "the most recent stimulus that triggered the anxiety" and "the anxiety itself, which would have attacked anyway eventually."
What Nyr does have is a Dissociated Cognition System, a device that filters out his emotions in the medium term so he can make more detached, functional decisions. However, the DCS isn't able to work indefinitely, he needs to intermittently remove it and process his emotions alone. To some extent, I feel like this is sending the message, "your emotions, good and bad, are both part of you, you have to deal with them eventually, but there are technologies that can help make this disease less debilitating." Which...I understand that this is an important message for people in our world to hear (myself included). But in-universe, with all the technological accomplishments of Nyr's world, including highly advanced spacefaring technology that they're very proud (even vain) about, this is still the best they can do? "Sorry, we can't take away the terrible bad feelings without dampening the good feelings too?" That can also be a dangerous/stigmatizing message, and just as a piece of in-universe worldbuilding, it feels a little bit like a cop-out.
The contrast between Nyr and Lynesse's perspectives on the world, and the ways this does or doesn't cause conflict, is nice. There's a lot of emphasis on language, and "just because I say X and you hear X doesn't mean we're necessarily getting the same concept across." And there's some clever foreshadowing in terms of the overall plot resolution. The book is a novella and a fairly quick read; however, that brevity means we don't get to learn a great deal about the demons; for all Nyr's scientific knowledge, there comes a point when even he has to shrug and go "okay, sure, we'll call it 'demons'." In terms of this subgenre, I tend to prefer worlds where we have time and space to dive into the science of even weird, adversarial threats.
But overall, "Elder Race" is a nice addition to a subgenre I really enjoy, so I give it a thumbs-up!