"What do you mean?"

"Like, they might have learned it, but you could learn one of those ciphers, too, it's just - when would it come up? Maybe it doesn't count if you know it but hardly ever use it."

"So, what, a language is picked by plain speak based on total use? You seemed to think it'd be weird for it to hinge on number of speakers when I suggested it."

"It seems like it'd be weird for it to hinge directly on that."

"I have no intuitions about it, it sounds as weird as any other hypothesis to me."

"If there were only two mortals, I'd expect to be able to talk to them, if they could talk to each other. If they couldn't, I'm not sure it would mean anything to be able to talk to them, because they wouldn't be - talking things."

"Hm. So, something like, the 'communicative power' of a language, you think?"

"Maybe."

"Hmm. How do I even test that. Er, I guess I could pick other languages and see if there's a consistency like that, but on the other hand plain speak did work on languages without any living speakers."

"It would also be weird if what I could understand changed because mortals died."

"Well, it apparently changes because mortals decide to invent stuff."

"That seems different."

"If you say so."

"Are fairy intuitions about this not interesting to science?"

"They are very interesting but a bit harder to directly experiment on? I mean, unless you have access to an array of intuitions you're just dying to tell me, that would be really nice."

"Nothing like that, it's just guesses as ideas go by."

"Yeah, that's what I mean by hard to experiment on. Do you have any guesses on why there's a difference between mortals dying and inventing languages?"

"...Because it's not determined in advance what mortals will invent to communicate with each other, but it's fixed what they used to do."

"Hmm. So your repertoire can only grow. And Al Bhed might never be in it because Final Fantasy ten was never as popular as Lord of the Rings."

"...sure."

"Hm?"

"I don't know what you're talking about but have no reason to believe you're wrong."

"Oh. Elvish was made for a work of literary fiction which became one of the most popular of its kind and decades after its release is still very well-known, and knowing how to communicate in elvish is not uncommon amongst the most avid fans. Final Fantasy ten is a video game and Al Bhed was the cipher-used-as-language I mentioned and some fans do speak it but much less and the game's not as famous as the book."

"Ah."

"We could try the other conlangs from this list and see if we find a correlation like what your intuition says."