Usually she'd put comparatively little stock in millennium-old legends, but this is a primary source, and the authors made some correct predictions on other matters, and the translator is good, and she double-checked to make sure the page numbers matched up so no one has been pranking her with inserted extra leaves. And the prediction is fairly dire.
And it's rather short notice.
Clarity tucks the book into a saddlebag and trots up to the main section of the palace. She can usually get an audience fairly quickly; Celestia has taken a particular interest in her since her admission to the School for Gifted Unicorns. This day is no exception. In fact, the guards usher her in even quicker than she'd usually expect.
"Princess, I have something urgent to tell you," Clarity says, mid-bow.
"Oh? What is it, Clarity?" inquires Celestia.
"I've found a prediction stating that on the longest day of the thousandth year -"
"Clarity," sighs Celestia.
Clarity grits her teeth; she's never told Celestia not to interrupt her. You can't tell the princess that. "Yes, Princess?"
"I have the utmost respect for your diligence at your studies, but you've got to take your nose out of those dusty old books now and again," says Celestia with a warm half-chuckle. "There's more to a young pony's life than studying. You're in the prime of your life, you're coming up on the end of what you can learn from school -"
Clarity stands up on all fours, no longer bowing, jaw slightly open.
"And," continues the Princess, "you need to make some friends. I worry about you all alone, you know. Weren't you invited to that party - who was it, Moondancer?"
"Yes, I was invited, but I barely know her," says Clarity.
"Perhaps the ponies around Canterlot just aren't clicking with you. You know what," says Celestia, as though seized with sudden inspiration. "I'm going to give you a job to do."
"...a job, Princess? But what about the longest day of the thousandth -"
"Clarity," says Celestia again, and Clarity shuts her mouth. "Don't you worry about it. I'm sending you to supervise the preparations for the Summer Sun Celebration. It's being held in Ponyville this year. I'll arrange a carriage for you. Pack your things, you leave in two hours."
"I..." Clarity can't really gainsay her. "Yes, Princess."
Celestia smiles.
Clarity bows again, and leaves, and packs.
-
She's in the air, drawn with her luggage in her carriage by someone in good condition for a long-distance flight - they're still working on that train line.
She steps onto the main street of Ponyville, laden with all her possessions in her saddlebags, and levitates her to-do list in front of her nose.
"Okay," she sighs to herself, peering at the first item. Clarity is pretty sure Celestia has read every book in the palace library at least once; probably she investigated the danger well in advance and dismissed it. (But Clarity will be staying in a library while she's in Ponyville, so she'll have a chance to double-check and find corroborations once she checks out the Summer Sun Celebration preparations.)
"First," Clarity mutters, "banquet preparations. Cheery Cherry Orchard."
"That sounds kinda boring. Unless you really like books, I guess. Do you really like books?"
"How much of the speed was them and how much of them was actual flying? I mean, could a unicorn or earth pony fly if one had a set?"
"Iiii haven't tested it with a unicorn or earth pony," she says. "For the very good reason that I have wings, so if something goes wrong, I can still fly. But in theory, yeah, anypony could do it no problem."
"Huh. If I were sticking around longer I'd offer to take them for a spin on the grounds that I can teleport."
"I'd have to make you your own set, anyway, the other problem is that I need my special talent to operate them - I deal really well with fiddly little things," she explains. "I guess you could use magic or telekinesis or something but these ones," she taps a hoof against the ground, "are designed to work purely by hoof. And they're very fiddly."
As someone who is often mistaken for some sort of musician based on the bell stamped on her flank, Clarity decides not to ask how exactly a flaming lightning bolt represents fine dexterity.
"Thanks!" She points a hoof at a building that just came into view; it appears to be made of a single large tree. "And there's the library."
Clarity lets herself into the library, intent on following up on that prediction as soon as she's worked out the categorization.
"Oh, hello!" she says, looking up as Clarity comes in. "Are you here for a book?"
"Uh... among other things. I'm in Ponyville on an errand for the Princess and I'm supposed to stay here until tomorrow."
"Oh! Okay," says the little pony. "That's odd, I wonder why the library? I guess it's free and everything, but... are you usually a librarian?"
"No. I like books, but I'm not actually a librarian. I do need to do some research incidentally, though." She starts peering at some shelves, trying to figure out what organizational system is at play here. "I'm Clarity Bell, by the way."
"I'm Blueberry! What are you looking for?" she asks, standing up. "I've been coming here practically my whole life, so I know where everything is."
"Unfortunately I was interrupted by the errand so I don't have much to go on. Key words include -" Clarity produces her current notebook. "Mare in the Moon, or, Nightmare Moon; and the Elements of Harmony." What kind of classification system is this? It doesn't seem to be arranged by author or in subject groupings. Is this literally alphabetical by title? Wow.
It is titled The Elements of Harmony: A Reference Guide.