"Good, good slower! That's it. Aaaand...dawn."
Luna leaned back into her room, out of the way of the blinding rays of morning sun that pierced the skyline. Twilight stumbled, exhausted by the effort of lifting the gargantuan orb above the horizon. She caught herself on the frame of Luna's door, panting heavily and stretching to keep herself from becoming sore later.
"That was...amazing," the overexerted alicorn breathed. "Was it...was it helping?"
"It was," Luna confirmed. "It helped a great deal, in fact."
Twilight held her breath for a few seconds before gasping and pushing herself to her hooves.
"It's...alive?"
Luna pouted thoughtfully as she considered the question. "...Perhaps that is a subject best left for my sister to explain." She reached out with her magic, conjuring tiny dragon-like hands to pull the great darkening curtain closed. "With or without its help, you did well," she smiled.
"Really?" Twilight asked hopefully, finally able to breathe again.
Luna nodded, a motion she realized was rendered invisible in the dark, then responded, "Very well. Though your success is clearly not without effort."
The purple princess sighed and rolled her head, causing her neck to pop and crackle. "It's just so...big. I've never lifted anything that size before."
"I should hope not," Luna chuckled, "Were it so easy my sister and I would be out of work."
Twilight snorted and nodded, sitting as she let her eyes adjust to the dark. "I'm still baffled by how the Old Unicorn Kingdom managed to do it every day."
"The magicks they used were not so simple as our method," Luna explained, trotting over to a couch and reclining casually. "A fitting simile to compare it to the Old Magicks of the Sky would be to call forth the juxtaposition of 'lifting with our knees' to using a rope and pulley. It is a brute force approach one that works, but one infinitely less viable for long-term use."
"Rope and pulley?" Twilight mused. "Like...how? Like putting it in a harness?"
"It is a crude, ill-fitting metaphor, upon reflection, but it suited the comparison," Luna shrugged. "In truth, it is more to do with gravity and temporal magick than actual movement."
The young alicorn blinked in surprise. "Time magic? How does that play in?"
"To set the sun and moon in motion, we create a vortex a gravity well, I believe modern astronomers call them and apply a decaying temporal manipulation that shifts the vortex throughout the night, or day, and sets our respective heavenly body on a path of our choosing. The effect could be described as making a tunnel out of instantaneous iterations of directed rings of gravitational pull over time."
Twilight stared in into the dark, eyes wide. "B-because making the actual tunnel would...take just as much effort as lifting it," she reasoned. "Just without the strain focused on the neck."
"Precisely," Luna nodded. "The effect, of course, can only be achieved once either body has cleared the Horizon Line, so we still need to push or pull them through to start the cycle, but once this is done we need only set the body on its path and the work is done."
Twilight shook her head in amazement. "How did they come up with stuff like that?"
"They didn't," Luna grinned smugly. "I did."
"You?"
"Well, both of us," Luna shrugged, "I'm sure Tia would be pissed if I didn't give her credit. And truthfully, the unicorns had come up with the gravity idea, and that resulted in a fair number fewer broken necks. But the time displacement. That was all me," she nodded, polishing a hoof on her coat. "Mostly."
Twilight continued to stare, nodding slowly. "That's why it's so difficult to do, isn't it? Time magic is even harder to pull off than...anything, really."
"Mm. And that's how we came to be who we are," Luna said thoughtfully. "The cycle of day and night represents the immutable passing of time, the ever present order that even Discord's Chaotic Magicks couldn't disrupt."
Twilight frowned. "But...Discord made it day or night whenever he wanted."
"Or," Luna agreed, "But never and. Even if their duration is shortened to mere seconds, the day and night and night always exist cyclically. Their order is absolute."
Twilight pawed at her chin, considering the other princess' words. "...What about during eclipses? Or that time before the Summer Sun Celebra "
"Ya gonna argue semantics all day or get to moving that sun?" Luna asked flatly, surprising her guest.
"Uh," Twilight stuttered, taken aback, "I...S-yeah, I'll...get to that." She stood and made to head back to the balcony, then stopped. "Wait, aren't you supposed to help me until noon?"
Luna shrugged. "You know gravity magic, don't you?"
"Yes, but not time magic."
"Who said anything about time magic? Look, here's a shortcut," Luna grunted, sitting up, "It's what I used to do before we figured out the time and order and yadda yadda. Make a vortex stronger than you need, at longer intervals, and pull it a few degrees at a time. You can do it every hour or whatever. You just have to balance out the force and catch it before it goes too far."
The purple princess pony slowly tilted her head, staring at the dim figure of Princess Luna in shock. "That...that's terrible!" she finally blurted. "Really?? That's how you used to move the moon??"
"Of course not!" Luna snapped, jumping to her feet. "The magicks of the sun and moon are vastly different. I connect with it much more easily than the sun." She sat again, turning her head. "It's just easier to move the sun like that," she pouted.
"That is grossly irresponsible, Luna," Twilight scolded. "What if you couldn't balance the forces? You could send the sun flying off into space!"
"Celestia has taught you well," the lunar princess groaned. "You sound just like she did a millenium and a half ago."
Twilight started to speak, but stopped. "I do?"
"Mm," Luna agreed, "Annoying. And naggy. Besides," she grunted, "I can calculate and balance gravitational forces better than anyone, even Celestia. There's no danger in my approach if you know what you're doing."
Twilight twisted her head, staring in disbelief at her mentor's kin, then blinked her eyes wide.
"Wait a minute," she breathed, "I recognize that kind of weak rationalization for minimal effort." She straightened up and pointed an accusing hoof at the other princess. "You're lazy!" she barked. "Sweet Celestia, you're lazier than Rainbow Dash!"
"'Sweet Celestia'?" Luna parroted. "Is that some modern expletive?"
"It's hundreds of years old!" Twilight answered, her voice still high with disbelief, "But that's not the point! These are heavenly bodies that Equestria- that the whole world needs to survive! You can't be so irresponsible with them!"
Luna groaned and stood as the smaller pony continued to berate her. A panel on the floor slid aside as she approached it, a very old and dusty chest rising out of it, and Luna fanned her face as it opened and spewed dust into the air. She peered into it and began to sift through the various artifacts within, keeping her muzzle shielded with a thin layer of magic from the dust that continued to float out of the old wooden box. After a few seconds of searching she removed a scroll, then turned and pushed it toward the still-talking princess of magic.
"...that you had to had to just throw the damn thing around like a What is this?" she asked, breaking her rant.
"'The Old Magicks of the Sky: Scroll of Sól'," Luna sighed, continuing to look through the chest. "One of the only written copies. Tia's is probably in better shape, but I don't know where she keeps it." She paused and lifted the remains of a weathered stone out of the chest, then casually vaporized it. "You want to see how hard it is to do these things? There you go. Sky magic."
Twilight looked between the scroll and the other princess for a moment before carefully unrolling the brittle parchment. She squinted, lighting her horn to try and read in the dark of the princess' chambers, but found that whatever was printed on the scroll was totally illegible.
"What is this? It looks like..." she mused, tilting the scroll. "Are there even words in here somewhere?"
Luna looked back at her with a smug grin. "Oh, I'm sorry. I had assumed the Princess of Magic would be able to read Partiki. It is the natural language of magic, after all."
The young alicorn scrunched her nose. "Of course I...have never heard of that before," she muttered, looking sideways. She looked over the scroll again, leaning close and tilting her head left and right to try and make sense of the various swirling and criss-crossing lines. After a moment of careful scrutiny she looked up at Luna and hesitantly asked, "The other one is written like this too?"
Luna lifted her head from the chest, still facing away and still grinning. "Hers is a bit simpler, if I remember right I copied it out in shorthand for her. But yes, it's the same language," she nodded. "The Old Magicks can't really be written any other way. They don't make sense otherwise."
Twilight nervously glanced at the scroll again. "...Not even in Old Cornish Runescript?"
Luna finally looked looked back at her, her infuriatingly smug face making Twilight's eye twitch.
"That 'throw and catch' method starting to sound good?"
Twilight leered at the other princess and rerolled the scroll, slipping into a pouch carried under one of her wings. "It's starting to sound even more like justification for laziness," she quipped. "If you can actually read this thing and you choose to use a brute force approach, that just tells me you don't want to put in the effort to do the job right."
"Like I said..." Luna started before yawning heavily. "T...Totally different magicks for the sun and moon. Just because I can read it doesn't make it any easier."
"Reading always makes things easier," Twilight nodded curtly, "And I'll prove it."
A hoof on her shoulder made her flinch and open her eyes. She frowned slightly as she found Luna sitting in front of her, her smile now tired and calming rather than annoyingly pleased.
"I hope you do," the lunar princess murmured sleepily.
Twilight adjusted herself as she realized the princess was trying to give her a bode of confidence and smiled back. "Uh...thank you?"
Luna nodded, yawning again. "I'll set up the framework of the time effects. You can handle the gravity bits, yes?"
"Y-Yes," Twilight perked up. "Leave it to me."
Luna turned her head toward the closed window and let her horn fill with a bright, crackling energy that dispersed with a cool blue pulse. She nodded to her guest, informing her that the effect was in place, and Twilight began running through her knowledge of gravity before realizing that the older princess was already nodding off. She smirked, gently nudging her elder toward her bed, and slipped out of the room to work on her half of the spell alone.