Smarty flew up to where Aurora was still climbing, now almost vertically. Instead of just using the rope for extra safety, she was now holding onto it almost completely independent from the wall.
"Yeah, it reaches all the way to the bottom, with some to spare. For not expecting to need it, you sure did bring a lot of rope."
"Well, I couldn't just cut a perfectly good piece of rope, now could I? And anyway, it turned out to be useful. It's not like it feels that much heavier. At least, not after Luna's been pushing us so hard. Besides, it never hurt to be over-prepared for something."
Smarty flapped her wings slowly, hovering next to Aurora and descending slowly to match her pace.
"...Mom?"
"Hmm?"
"Did you let any of the Princesses know where we were going?"
"Not really. But Celestia pretty much gave us free rein of Canterlot for our free time. We should be fine."
"...Can this still even be called Canterlot? I mean, we're pretty much inside the mountain now. And with my directions all messed up, I can't even be sure we're under the city anymore."
"I don't think Celestia will mind, personally. She already knows I might visit the old study. And we haven't exactly gone that far, at least not laterally. We still should be underneath Canterlot."
"All right, but if we get in trouble for this, it's officially your fault."
Aurora rolled her eyes. "Yeah, sure. Fine."
Aurora's back hooves touched the smooth, crystal floor and she let go of the rope, her front hooves falling to the ground.
Smarty landed beside her. "So... where do we go next?"
"I think we should go get the rope, though. We might need it again soon."
"All right, all right. I'll go get it." Smarty flew back up the passage, and a few seconds later, the rope fell into a pile by Aurora's hooves. Not bothering to re-coil it, she shoved it into her saddlebags as Smarty flew back landing neatly beside her.
Aurora looked at her in surprise. "You're getting a lot better at that, Smarty. I barely heard anything that time."
Smarty rolled her eyes, but couldn't contain a smile. "I have been practicing, Mom."
"Yes, well... it's working. Anyway, which way do you want to go?"
Smarty looked at the wide passage in front of them, that split in two. "Uh, well, if I had to pick... I mean, they look pretty similar... maybe the one on the left? It's slightly wider. But I really don't care that much."
"All right, left it is, then." Aurora started walking, but quickly stopped as the path split again almost immediately. She turned her head behind to look at Smarty. "Which way now?"
"I don't think it really matters. As long as we remember which paths we already went on, and that compass of yours works properly, we should be fine."
Aurora looked down each path critically. Let's continue left again. It's easier to remember. And I don't really want to rely on my compass. The only function that works on it would require us to retrace all of our steps. I would much rather just remember the way out.
"Also, the right path seems to slope downward. I'd like to explore the upper parts of the cave before we go much deeper."
Smarty shrugged her wings. "Seems fine to me. It's your expedition."
Aurora paused, turning her body completely around to face her. "It may have been my idea to go here, but I wanted to explore with you. Are you still having fun? We can go back at any time, trust me. I won't be mad."
"No, no, it's still fun. I like to explore these kinds of places. It's just... I don't see the point of dithering on which direction we should go. I mean, I'm really interested in the way these crystals reflect magic, but we already have the sample we need to test things. And if it's just for fun that we're exploring, then it doesn't really matter which path we take, does it?"
Aurora nodded, walking farther down the passageway and into a large cavern. "Well, most of it is just for fun, but but some of it comes from something I noticed when I was studying in that room with all those books. I hadn't really thought of it as anything special at the time, but that room was not a place of storage. It was a room that ponies used. So, while I might be horribly wrong about this, I was hoping to find some evidence that could prove ponies used these caves in the past, and maybe even find more places like it."
"...um... do you mean like this?"
She whipped her head around, looking at the place Smarty was now pointing at. There were several long scrape-marks in the otherwise perfectly smooth cavern floor.
"...Yes, actually," she said in surprise. "Good eye!"
Smarty blushed.
Aurora put a hoof to her chin. "Now, what do these markings mean? Normally, I might say that ponies might have been mining here, but there are only three of these markings. Besides, this is what pickaxe-markings look like in stone."
"Yeah, crystals would just shatter."
"Precisely. Marks like this could only mean that either there was slow wear from continuous use, or just the movement of something really heavy. I would suspect the latter, due to the fact that there are only three markings like this. There should be many more faint-looking ones otherwise." Aurora looked up from the ground at where Smarty used to be, but she was already looking at something near the far side of the cavern.
"There's something over here, too. Some sort of... rectangular depression. It's kinda faint, but definitely here. I think some sort of heavy object was kept here, and later removed. Based on the fact that this is crystal, though, it had to have been there for a long time."
Aurora walked over to the place where Smarty was standing and looked into the worn depression.
"Huh. Yeah, you're right. Ponies were here, all right. We just don't know what they were doing here, or even why."
Smarty walked into the center of the cavern, stretching her wings carefully. "Or who they were. But if they are connected with those books you found, they must know a lot about Earth Pony magic. Things they kept secret."
She walked to the opposite side of the room and gestured at another similar indentation. "And whatever it was, it must have been a large operation."
Suddenly, she froze, looking not at the markings on the ground, but at the floor beside those markings.
"No..."
"What is it, Smarty?" Aurora asked, walking over and examining the area Smarty had seen.
"Mom, do you notice anything about this spot here?"
"Uh, not really. There's nothing really there."
"Exactly."
"What do you mean?"
"This floor is smooth."
Aurora jumped, and her heart felt like it had just fallen five stories. She realized that she knew this texture of crystal all too well. She had felt it daily for most of her life. It was the texture of crystal that had seen continuous use for several years. She put a hoof to her chest.
"Smarty... all the passages down here are just as smooth.
"Do... do you know what this means?"
Smarty dragged her front hoof along the cavern floor. It was so smooth, she could barely feel even the slightest imperfection.
"It means that this is larger than we ever thought."
Smarty tapped Aurora on the shoulder. "Um, Mom? The castle entrance is over there. I mean, it isn't exactly subtle."
Aurora rolled her eyes. Again with my lack of directional sense. "Yeah, real funny, Smarty. But we aren't going back to the castle. At least not yet. I want to check out something first at CSGU."
"Um... what?"
She shook her head. "Sorry, Smarty. I wasn't paying attention. Just Celestia's school."
"C...S... ah, okay. I get it. Why do we need to go there, though? Weren't we about to start practicing soon, anyway?"
"Yes, of course. I wasn't going to take that much time. It just had occurred to me that as Celestia's student, I'm also technically enrolled at the school that has her name, even if I'm not attending any classes there. I figured we might be able to take advantage of the testing equipment there, when we decide to figure out what that crystal is."
"Sounds like it makes sense. They would have the best equipment. At least, the non-confidential stuff. But shouldn't we do all of this later, when we have time to go through with all the testing? I have a feeling a complete analysis will take longer than a few minutes."
Aurora shook her head. "You're half right. We will do all the testing later, and the analysis will, most likely, take a long time to get definitive results. But if we know where everything is beforehoof, it will maximize the time we have to do the interesting stuff. Also..."
She lowered her head, giving Smarty a sheepish grin. "I may have forgotten to contact a certain friendly receptionist pony when I made it in."
Smarty smiled. "Yeah, she was nice..."
Aurora's eyes widened, and she suddenly stopped, causing Smarty to bump into her from behind.
"Smarty... what was that?"
"Um... she's nice?"
Aurora turned back, looking her directly in the eye. "...Smarty... you weren't there. You... you didn't exist yet. How do you know about her?"
Smarty opened her mouth to respond, then closed it suddenly, sitting down with a thoughtful expression. She scratched her head. "Huh. I don't really know. I just sort of... remember her."
Aurora put a hoof to her chin. "Do you remember anything else? Any details about her? if we could find out where you got these memories, it would be incredibly useful. Anything will help."
"Uh... well..." Smarty scrunched up her face. "I think it might have been from... your perspective? I don't remember anypony else being there. Except maybe a few snobbish ponies sometimes. I don't really remember all that much. Mostly just the emotions. I do remember that she was a unicorn, though. That seemed important, or something."
Aurora looked back at her intently. "So you don't remember any details? Like her mane color? Or her name?"
Smarty stood back up. "No, not really."
"Huh. Well, I'm not sure how, or why, since there wasn't really much detail-"
"Sorry."
Aurora shook her head. "No, it's not your fault. Anyway, we can at least deduce that somehow, you got some of my memories when I ma... I mean, when you were born. But I don't even understand how that was possible! The kinds of magic I used had nothing to do with memory whatsoever."
Smarty stretched her wings, flexing each group of muscles individually, then took off, hovering close to the ground. "Yeah, that is kind of strange. But that should probably wait until later. For now, I believe you have somepony to catch up with."
Aurora pushed open the door, waving to the pony at the receptionist's desk.
"Hi, Meadow!"
The tan unicorn, Meadowlark, turned and smiled in recognition at the familiar face. "Aurora! It's nice to see you again! And who is this fine young mare next to you?" she asked, looking in Smarty's direction.
Aurora looked beside herself. "This is Smarty Pants, my... my sister."
Smarty looked at her quizzically. Huh?
I think Celestia wants us to keep this a secret.
Wait, she told you it was confidential? She didn't say anything to me.
No, but... I just think it's something she might do. Just play along.
Meadowlark continued, oblivious to their private exchange. "Well, it's nice to meet you, Smarty Pants. Anyway, Aurora, was there any particular reason you're here? I kind of doubt you would walk all the way over here just to see me." She chuckled.
Aurora walked closer to the desk, Smarty in her wake. "Actually, yes."
"Yes to which one?"
Aurora opened her mouth, closed it, then laughed. "Both of them, actually. I was going to do it later, but I realized I hadn't seen you in a while, so I decided to come over anyway. I wanted to see the feasibility of using the testing equipment here. I am technically enrolled, so why waste the opportunity?"
Meadowlark blinked, taken aback. "Wait, you were accepted? This is great! Why didn't you tell me? And shouldn't I have seen you by now? School started a few weeks ago."
Aurora grinned sheepishly. "I'm really sorry I didn't tell you. Everything just went so fast... I guess I just forgot that you didn't know. Well... I obviously did get accepted. And I am enrolled here. But you haven't seen me, because... well, because I got accepted by Celestia, not necessarily the board."
Meadow's mouth fell open slightly.
Smarty tapped Aurora on the shoulder. "M... I mean, Aurora, a new student of Princess Celestia is a big deal."
"No kidding..." Meadowlark muttered to herself.
"...so wouldn't everypony already know about it by now?"
Meadow suddenly froze, her eyes wide. "Um, Aurora, I think you might want to avoid mentioning your... status... to others for now. If the Princess hasn't made an official statement about it yet... she probably has a good reason."
Yeah, she thought to herself. A very good reason. This will not go down easily with the nobility. They made enough fuss when that guard captain was established a while back. And that was simply because he wasn't a noble! This... this will not end well.
An image flashed through her head, an image from a very memorable trial she had the privilege of attending a few years ago. One of the Council members had slipped up in her frustration, and had used a tribalist slur. She didn't think she could ever forget Celestia's face in that moment.
She smiled. This may not end well... but at least it will be entertaining to watch.
Aurora sighed. "Yeah, you're probably right, Meadow." She put a hoof on her chin. "I really need to have a talk with her, though. It's getting hard to tell which things are classified and which things aren't."
Meadowlark chuckled. "I think for now, you should just treat everything as a secret. Nopony even knows you're her student yet. You can't mess it up if you are over-careful."
"Yeah, that's probably a good idea... so, um, is it okay to use the equipment?"
She smiled, shaking her head. "Oh, Aurora, I doubt anypony could bar you from using it. Still, if you are going to be using it often, you should probably use the castle's entrance to the school. We don't want ponies getting the wrong idea."
"Or the right one."
Meadowlark laughed. "Exactly. Besides, all of that sort of equipment is stored right near that entrance, anyway, in case their Highnesses need to use it. I hear that Princess Twilight takes advantage of that frequently."
Smarty chuckled. "Yeah, that does seem like her."
She stretched her wings, turning to the door. "Well, we should probably get going. We need to go... study... in the castle soon."
Aurora blinked in surprise. "Oh, right! Well, Meadow, I'm sorry I couldn't stay much longer. Um... I'll try to visit soon!"
Meadowlark smiled warmly. "And I look forward to it. But don't put me before your..." She looked briefly at Smarty. "...studies. Well, it was nice to see both of you ! Enjoy the rest of your weekend!"
Aurora grinned. "I will! See you later!"
Meadowlark watched as the two fillies left through the large double doors. She waved.
"Bye!"
Such interesting young mares...