(4) Upon that day each year, which shall be established as the 90th day following the New Year, shall one score of the most powerful unicorns, of age not less than two and twenty, take upon themselves the direction of both sun and moon for a period of not less than four and twenty hours, and neither shall either alicorn aid nor disrupt their practice in any way during this time.
-Excerpt from the Magi Carta
Twilight and Celestia watched from one of Canterlot Castle’s many parapets as, below them in the bailey, twenty unicorns shuffled about, testing and preparing an elaborate arcane circle in the predawn darkness.
“It’s not fair,” grumbled Twilight.
Celestia nodded diplomatically. It was a nod she often found herself using during court, one which suggested agreement without actually committing her to more than acknowledgement.
Twilight knew that nod all too well.
“It’s not,” she said, emphatically. “The document says ‘either,’ not ‘any.’ The signers clearly meant you and Luna!”
Celestia nodded again. “The Unicornian leaders certainly were thinking of me and Luna when that document was drafted,” she said. “Of course, there were no other alicorns in Equestria back then.”
Twilight sighed. “I know. It’s just… I’m finally old enough to take part in the solunus circulum! And now, even though I’m perfectly qualified, I can’t.” Her ears drooped. “This is something that I’ve dreamed of doing ever since I was a little filly. It’s one of the most important historical traditions of ponykind!”
Celestia extended a wing over Twilight’s back, offering a gentle hug. After a moment, Twilight leaned into her. Neither spoke right away.
Eventually, Twilight gave a dry chuckle. “I guess you probably know what it’s like, not getting to control the sun, though. You have to watch this every year, after all.”
Celestia pursed her lips. “Twilight,” she said, “I’m sure you aren’t upset just because you don’t get to move the sun and moon around.”
Twilight tried to chuckle again, but the sound died in her throat. Instead, she simply shook her head.
“What is it, then?”
Twilight didn’t answer immediately. When she did, she looked up to the sky, her gaze wandering as if tracing the path of the still-absent sun. “I guess it’s not really about the sun and moon at all,” she murmured, as if talking to herself. “I mean, I already got to control them once. When I had your power.” She paused, and Celestia waited patiently for her to continue. “It wasn’t the same as what the circulum does, of course, but if all I cared about was getting to do some hooves-on astronomy… well, I’ve already done that.”
“But there’s something else?” Celestia prodded.
“It’s just… every great unicorn I’ve ever read about, in any of my textbooks—hay, in any of the fiction I read—it always tells you how many circulums they took part in. It’s how you know they were great! And I—”
“You want everypony to think that you’re great?”
Twilight’s cheeks flushed. “Oh, no, I didn’t mean that I…” She trailed off as she turned to look at Celestia; she was smiling a bit too pleasantly. “You’re mocking me,” Twilight said, more sourly than she had intended.
“A little,” Celestia agreed. “But only because I know that fame isn’t what’s bothering you. Tell me, why is this really important to you?”
Twilight looked back to the bailey. “I guess it’s that… it’s that this, right here, is something that all of my heroes have done. This exact spell, together with nineteen other unicorns, for this exact purpose. It’s been this way for thousands of years, like a string that goes all the way back to when ‘Unicornia’ was more than just a fairytale setting. A string that winds back to the times only you and Luna can remember, and that snakes forward even to today. A string tying every wizard and mage together, all the way back to Star Swirl the Bearded."
Her eyes returned to the sky, and after single hard sniff, she continued. “For as long as I can remember, taking part in the circulum is something I’ve fantasized about. I’ve daydreamed so many times about taking the same stance within the casting circle as all my heroes once did, of joining together with the other casters in the same way that they all joined their contemporaries. So many times, I’ve imagined myself as a part of the circulum, following in their hoofsteps.” Through her wing, Celestia could feel Twilight’s body tremble slightly. “Maybe it’s self-aggrandizing, but… but I really wanted to be a part of that. I wanted to pluck that string, to touch all of that history. I wanted to be a part of something that binds all of my idols and inspirations together.”
Celestia didn’t speak until she felt the tremble stop completely. “You know the reason why the Unicornians insisted that Luna and I relinquish the sun and moon once a year, don’t you?” she asked.
“Yes,” Twilight answered. “So that if anything happened to you two, there would still be wizards who knew the spells to keep the cycle of day and night, and who’d performed those spells before.”
Celestia nodded. “If something were to happen to me—well, something already did. And when Tirek came, it fell to you to take my and Luna's places.” She smiled. “Though thankfully, only for a brief while. But even today, with four alicorns in Equestria, it’s still all too easy to imagine some new foe capturing all of us, or finding some way to strike at our power. And if something were to afflict us, it’s important that there be unicorns ready and able to step up and ensure the cycle of day and night continues.”
Twilight nodded. “I know. It makes sense to exclude me, really. It would be silly to let me take part.”
“Yes, it would be.” Celestia paused. “That doesn’t make it feel any better, does it.”
“No.”
They lapsed into silence, then.
And together, they watched the sun rise.