"Rainbow?" I stepped into the Golden Oaks library, diligently searching town for my chromatic friend. "Rainbow, are you here? I waited an hour, and if you’re napping somewhere -  " I stopped. An excited voice filled the normal stillness.

The library was quite small, but it did have a few alcoves, nooks, and crannies. I carefully walked around the room, until I found the source of the lecture. Twilight was pacing determinedly in front of a blackboard, scrawling symbol after symbol, talking non-stop. Sweetie Belle, eyes glazed in incomprehension, stared at the raving unicorn with a slack jaw.

"So you see, if the entrapment vector is rotated entirely through the matrix, the net delta is zero. This means the klein field is fully re-directing the energy, and - "

"Twilight."

" - also, the crystalline structure is cubic, but with skew edges, so for every fifth set, the entire loop is shifted one step - "

"Twilight!"

" - so, flat fields bent through space have much higher deflection coefficient! Any questions?"

"TWILIGHT!"

"Yes, in the back! Wesley Kilmer!"

"Twilight, what are you doing?"

"Teaching Sweetie Bell magic." Twilight gave me an innocent stare. I glanced back and forth, from the chalk-dusted teacher to the nearly comatose student.

"Uh - huh. Why, if I may ask?"

"She asked!" Twilight gave me a grin. "She's interested in magic! Isn't the joy of learning wonderful?"

"Um, Sweetie?" I nudged the filly. "You awake?"

No response.

"Well, um." I turned back to Twilight. "Couldn't you have started with the basics?"

"This is basic, Wes." Twilight frowned pedantically. "I need to challenge my students, or they'll get bored. Learning shouldn't be boring!"

"Twilight, this is advanced field theory! There's nothing 'basic' about it!"

"Nuh - uh!" Twilight levitated a textbook off the table. "It is so! Look at the cover! Basic magical theory!"

" - for thaumic defense engineers! Twilight, this is college material!" I facepalmed. "Seriously, this is the same as when I 'helped' you with Cherilee's class! You need to be more aware of your audience!"

"This is nothing like that!" Twilight looked nervously at Sweetie, the glassy expression of her student seeming to register. "…is it?"

"It totally is. Look, Twilight, you're a great lecturer. But this is just way, waaaay, beyond Sweetie's level. And you're not even explaining! You're just working proofs!"

"But…" Twilight gave me a lost look. "Isn't the rest self-study? This is usually enough for Spike."

"Spike is immature, not un-educated! He's referenced this book enough, he could recite it in his sleep." I sighed. "Look, how about you go… make some tea, or something, and I'll take a shot at teaching Sweetie Belle. Then, when I've covered the basics, maybe she'll want a little advanced explanation?"

"Oh." Twilight's mane and tail drooped. "Okay." She trudged out of the room. I rubbed my eyes, and thought for a second.

"Right, that’ll work," I mumbled. "Look, Sweetie! Your cutie mark!"

"Huh?!" Sweetie leaped into the air, turning to look at her flank. Her face fell when it was still blank. "Oh, it was a dream." She looked down, dejected. "I guess I couldn't learn anything from Twilight, after all. Am I a really bad learner?"

"No, hey, cheer up, Sweetie." I leaned down to give her a hug. "Don't fret about not understanding Twilight. She's a great lecturer, but not much for actual explanations. What did you ask her to teach you?"

"I just wanted to know a little more about unicorn magic. You know, how it works and stuff." She sighed, hugging me back. "I'm not very good at it, but Twilight is. I thought maybe if I learned a bit more, I'd be better."

"Not a bad idea." I released her and pulled up a cushion, sweeping books and paper off the table and flipping the chalkboard so a clean slate was available. "Maybe I can help."

"You?" Sweetie gave me a blank stare. "You're not a unicorn."

"Sure." I shrugged, and pulled out my wand. "But I do have this."

"What's that?" Sweetie poked it.

"It's called a wand." I spun it around a finger, drawing crackling trails in the air. "I can use it for magic. Just a little bit; probably even less than you."

"So… you know magic?" She gave me an unconvinced look.

"Yup." I levitated a sheet of paper, carefully folding it into a paper crane and flying it around her head. "Unicorn style. I'm not too bad, if I do say so myself."

"You can teach me magic?" Her expression lightened a little.

"Not spells." I shrugged. "But maybe I could teach you something else."

"Huh?" Her expression was intrigued, now. "What else is there?"

"A very good question." I grinned, just as Twilight came back with tea. She poured three cups, before slumping quietly by the window and picking up a book. "Let's explore it." I blew the steam off my cup, and tasted it. "This is too hot. Can you chill things yet, Sweetie?"

"I'm not very good." She looked at the cup nervously.

"Give it a try." I grinned encouragement. She nodded slowly, and concentrated. A dim green mist flowed off her horn, settling across the tea. I sipped, and nodded. "It's definitely cooler. Not bad." She smiled. "Now watch." I raised my wand, and pushed just the barest hint of magic through it, waving it over her cup.

Ice crackled across the surface.

"Woah!" She looked at the cup, and then at me, and back at the cup. "You… what… I could barely feel that! How did you do it?"

"Simple. Vision. In school, have you talked about the basics of magic yet?"

"Some." She frowned. "But I'm not sure I really understand them."

"Can you repeat them for me?"

"Miss Cheerilee says magic is made up of two things; the energy to create, and will to direct." She looked at me uncertainly, and I nodded. "She said harder spells take more energy, and more complicated a spells are trickier to imagine."

"That's a good start." I smiled at her. "Those are the basics. Energy and will. So, tell me, Sweetie, when you cast a spell, what do you do?"

"Um." She gave me an uncertain look. "I… think about it, really hard, and I sort of push…"

"Alright." I nodded. "That sounds correct. When you do that, you're engaging both of those basics. The thinking is your will, and the pushing is your energy. If you do something complicated, is it trickier to think the right things?" She nodded. "And if you're doing something hard, you have to push more?" She nodded again, more firmly. "There you go. Will and energy. Those are the basics."

"So how…" She looked at the tea, and then back at me.

"Well, like most things, there are tricks." I waved my wand over her cup, and it started steaming again. "Magic is no exception. Think about this. When you willed your spell, what did you imagine?"

"I just.. .thought about colder tea."

"Well, that's not bad." I shrugged. "In fact, it's definitely enough, if you've got lots of energy." I bit my lip. "I'm going to try and be a bit more technical here, so if you get confused, let me know, alright?" She nodded. "Okay. Will and energy are the basis of all magic. But, both will and energy are actually pretty complex." I pointed at the tea. "When you think about 'colder', you're taking a concept, 'cold', and applying it to the tea, which is hot. You then add energy, and the energy makes your will happen. With me so far?"

"I think so."

"Okay, next step. Cold is a word that defines a concept. But, do you really understand what that concept means? Think about it for a moment."

I sipped my tea, watching her mull it over.

"Cold is what happens in winter." Her voice was quiet, reflective. "I feel it in the air. Cold is the opposite of hot. Miss Cherilee says cold is… temperature is…" She paused. "This is hard."

"Yeah, lots of things are." I shrugged. "Okay, let me explain a bit. Cold and hot are opposites, but they're both caused by the same thing; movement of molecules. Everything is made up of tiny, tiny pieces called molecules, even the water and this cup." I tapped the cup. "The hotter those pieces are, the faster they move. The colder they are, the slower they move. So, instead of just thinking about 'cold - the opposite of hot, the feeling that happens in winter,' I thought about 'cold - the molecules of tea are moving slower.' More than that, I didn't think about 'change cold to hot', I thought about 'take the movement away from the tea molecules, and give it to the air molecules'. This is vision, the first step to using will more effectively." I sipped my tea again. Sweetie sat, thinking, for a good minute, before nodding slowly.

"Okay." She gave me a serious stare. "I think I understand, at least a little. You're saying that the more I know about something, the better I can will it to happen."

"Basically." I grinned. "And the better you can will something to happen, the less energy it takes." I waved my wand. "Remember, magic can do just about anything. You're limited by only those two things; will and energy. If you've got enough energy, and you really, really know what you're doing, you can do things like this." I focused, and an illusory flower grew from my wand, sprouting from a twig into a bud, and blossoming into a profusion of blooms.

"Coooool." She gazed at the flower in awe. "How are you doing that?"

"Illusion magic is complicated." I grimaced. "I can't give insight here until you've done a few more years of school." Her face fell. "But, maybe…"

"Yeah?"

"Just a second." I stepped into the library proper. Scanning the shelves, I spotted the one I wanted. I flipped it open, and showed it to Sweetie. "Have you seen these?"

"Magic Eye?" She gave it a dubious glance. "What is it?"

"It's an illusion grimoire."

"Huh?"

"It's a spellbook, filled with rune-circles for casting illusions."

"But it's a picture book!"

"Well, that too." I smiled. "Look, it's supposed to be fun. But it basically does what I just did. All you need to learn is spell-circles."

"Is it hard?" She looked up, green eyes wide.

"Not at all." I pointed to the page; it had a background of trees, painted with lush green foliage. Runes and circles were cunningly concealed in the illustration. "Can you see this marking, here?"

"The star?"

"Yeah. That's the key for the spell-circle. They can be anything, but this book uses stars. All you need to do is will your energy into the star. Like this." I tapped my wand to the key, and pushed power through. It didn't take much, but I gasped as I let up; even a children's book was a challenge for my meager reserves.

The runes slowly lit, tracing the circle with my crackling orange aura, before fading. For a second, multicolored birds peeked from the foliage, jewel - like feathers shimmering, before they faded.

"Woah." Sweetie gave the book a look of innocent wonder. "That's cool! How does it work?"

"Ah, you're curious about runes, now?" I grinned. "That sounds like advanced instruction." Twilight's ears pricked. "Maybe our local librarian would oblige?"

"Um…" Sweetie gave her a cautious glance.

"It'll be fine. Twilight's not a bad teacher; she just gets carried away. Use small words, Twilight, and talk slowly."

"Right!" Twilight bounced to her feet, enthusiasm for learning restored. "Okay, Sweetie, do you know what a rune does?"

"Um… something for spells?"

"Yes! Runes are precisely a means of storing a vision." She pointed to the book. "The reason you can cast an illusion using this grimoire is because the runes hidden in the page contain the will for your energy. You push, and the circle does the rest."

"Oooooo." Sweetie looked at the book again. "So, if I learn to write in runes, could I cast spells like that?"

"Yes!" Twilight nodded eagerly.

"Okay! Teach me about runes!"

"Okay! Runes, or as they're technically called, phenomenotation, are an ancient art. We've expanded and refined the science several times! First, you need to memorize this!" She levitated the basic rune dictionary onto the table with a thump. It was the size of a small encyclopedia. "Then, when you've got a grounding in all the different schools, we can move on to simple circle construction!" She added another textbook with a thwap. "Once you can make basic circles, we'll expand in the direction that interests you, by picking a single school and focusing on that, while continuing to study the mechanics of construction!" She grinned, adding another two books. By now, the pile was almost as tall as Sweetie. "If you study this in your own time, you should be writing rune circles in a few months!"

"Um…" Sweetie peeked hesitantly around the column.

"Oh." Twilight glanced at the books, and wilted slightly at the look on her student's face. "Too much?"

"Maybe a little." I shoved the books to the side. "Sweetie, runes are really, really useful. But writing your own rune circles is an advanced topic, and normally the sort of thing only experts do. And there's a very good reason for that."

"Okay?"

"See, it comes down to something Twilight mentioned before; schools."

"Blech." Sweetie stuck her tongue out. "School."

"Not like that, silly filly!" Twilight giggled. "No, schools are categories for spells. Different runes are for different spells.  They go in groups, like fish! So, runes for spells that move things around go into Kinesthism, and spells that change the way things in the world work end up in Bizzanarchy. Sound magic falls into Echonarchy, and the chilling spell you and Wes practiced earlier is part of Entropology!"

"I'm with Sweetie Belle on this, though." I crossed my arms. "Schools are dumb."

"Oh, come on, Wes! We can't just throw the whole system out the window!"

"I don’t' see why not." I pouted. "They barely make sense!"

"Um…" Sweetie glanced inquiringly at me. "What do you mean?"

"Okay, the idea behind schools is this." I tapped the rune dictionary. "This book has several different sets of runes, all invented by different researchers. Each set reflects their 'vision'. If you arrange them in different patterns, you can use that pony's vision to help your spellcasting. So, say I made up a set of runes to reflect my vision of heat." I pointed to the tea. "You could use it to cast the chilling spell using a lot less energy, even if you didn't understand how I imagine heat."

"Oh." Sweetie sipped her tea. "That sounds useful, though."

"It is. It's not until the next step that things start getting complicated." I grimaced. "The problem is, that various researchers don't always understand the same things in the same way. What if I imagined cold as something that happened in winter… and only in winter? That would affect my spellcasting. I might not even be able to cast chilling spells in summer, and if you used my runes, you couldn’t either."

"That's dumb." Sweetie gave me a wide-eyed stare.

"Right! And that's what happens with schools. The divisions are completely arbitrary, based on what the ponies who invented the runes actually understand. So, some runes that work together shouldn't, and some runes that don't work together should. On any spell using more than fifteen runes or one school, reliably calculating energy requirements is impossible, and unwanted interactions play merry hay with the intended effects!"

"Language, Wes." Twilight gave me a reproving glare. I gulped guiltily. "And the effects of most runes are well researched. You wouldn't have those problems if you used them in a traditional manner."

"Tradition is great, Twilight, but there's no reason to keep it if it doesn't help." I frowned. "Look, Sweetie, here's the thing about runes. They're really useful. Really, really useful, in all sorts of ways. The thing is, they don't actually make spell-casting any less work. Actually, they usually make it more work, because you end up with these strange problems, where your circle doesn’t do what it should, and you need to figure out what the runes are really doing, and then change it so they stop." I sighed. "Remember that floating spell Twilight and I worked on?"

"Yeah?"

"Lots of ponies thought it was pretty cool. And not just because it lets you float in the air. The reason it got lots of attention was because it combined runes from different schools; runes that ponies thought didn't work together. The reason we could make that work, was because we understood what was really happening better than the ponies who wrote those runes. Our vision was better than theirs, so we could do things they didn't understand. It was a lot of painstaking research, though, because before we could modify the spells, we had to really understand the vision behind the runes, so we could see what the magic was really doing."

"So, can you make up your own?"

"That's… tricky." I tried to give an explanation that would fit. "The thing is, I don't know runes like Twilight. And Twilight doesn't know my vision of the world. We could… at least a little, if we could mix those two bits of us together." I thought of Arglefraster, and some of the effects we'd managed. "It would be pretty useful. Unfortunately, there's no simple way to do that, and besides… some of the things runes do, I don't have any vision for at all. The school system is stupid, but it's a very, very well developed stupid. Sometimes it's better to stick with an inefficient tool you understand than switch to a new tool you don't. I don’t actually plan to re-write the system. I just like to complain."

“Oh.” Sweetie Belle grinned at that. "But… how do they know?"

"Hmm?"

"How does the magic know what the runes mean?"

"That…" I grimaced. "Ponies have debated that for years. There's a field of study called subthaumology where all they do is argue about it. Nopony can agree."

"Although there are many fascinating theories!" Twilight interjected, with a grin.

"Yes." I gave her a flat stare. "Maybe you can read about them later, Sweetie. But in short, the magic knows what the runes mean the same way it knows what your thoughts mean; because it's magic." I shrugged. "If we knew more about that, we might understand how cutie marks work, and other interesting things about this world."

"Cutie marks!" Sweetie gasped. "We don't know how they work?"

"Not at all." I shrugged. "We know a lot about them, but mostly what they do, not how."

"They give you your special talent!" She struck a hoof on the table.

"Right… sort of." I shrugged. "They give you some boosts, too. They're sort of… a vision magnifier?"

"Huh?"

"Like… you know, will and energy. Vision boosts will. Well, cutie marks boost vision. Lyra, for example, has a cutie mark that uses music. Because of that, she can cast sound spells - echonarchy - a lot more easily."

"Like my sister, and her gem finding spell?"

"Exactly. We don't know why she gets a boost there, but she can locate gems much more easily because of her mark. Actually, cutie marks are more flexible than most ponies realize. Rarity could probably cast spells to locate anything more easily, although the boost would be less. Lyra can do some pretty surprising things, because she spent several years exploring all the stuff she could use her cutie mark for."

"Cooool."

"Yeah, it's definitely an under-researched field." I shrugged. "Okay, to wrap up runes, there's only two more things to know. The first one is artifacts."

"Like the Elements?"

"Yes, exactly." I grinned. "All artifacts are based on runes. If you take a whole spell, with everything needed to cast it and write it into a thing, it becomes an artifact. Grimoires are the most basic." I tapped the Magic Eye book. "It's a thing that's magic. If you put energy in, stuff happens. They can be as simple as a chalk circle, or as complicated as a flying carpet. They're all based on runes, and they all follow the same rules. Somepony did the research, built a spell that worked, and then attached it to a thing to make a useful tool. Even the Elements are made things."

"Although we don't know if a pony made them." Twilight added.

"The other thing to know about is runecasting."

"Rune… casting." Sweetie Belle sounded out the word. "What's that?"

"Another simple idea that's tricky to get right." I grinned. "Okay. You wanted to cast illusions like I did?"

"Uh-huh."

"Well, if you like the illusions in this book, you might be able to cast them." I pushed the Magic Eye book a little closer to her.

"But I thought you said…"

"Yeah, illusion magic is complicated." I shrugged. "That's why runecasting is useful. If you're really motivated, check this book out, take it home, and memorize it."

"Memorize?" She gave the book a dubious look.

"Not just the pictures; memorize the runes. Go over every square inch of the page until you can picture the whole thing in your mind, clearly. Until you can read it in your mind. Then you can try runecasting."

"How?"

"Kinda like casting using the grimoire." I shrugged. "You imagine the runes, and pretend they're appearing somewhere. Then, you push your magic into the key, and the spell will work."

"Hmmm." Sweetie looked at the book again.

"Would you like me to show you?" Twilight flipped the book open, and glanced at the page.

"Yeah, but - " Sweetie cut off as Twilight touched the table. A small rune-circle appeared under her hoof, glowing magenta. She lifted her foot, and multicolored birds winked into view. They looked a little odd without the illustration, but it was undoubtedly the same.

"She's got unfair advantages." I gave the stunned filly a shrug. "Twilight has practiced magic so thoroughly, she can memorize a tiny circle like that with just a glance."

"Oh."

"The disadvantage to runes and runecasting, is that they actually take more energy than casting from your mind." I tapped my head. "If you have the concepts in here, the spell works better. The thing is, it's sometimes easier, or at least more stable, to use runes or rune-casting. If you write a spell in runes, you can 'compile' it into concepts, using special rules. Most spellbooks have both types of spells. But casting from spellbooks is even trickier than runecasting, so we won't talk about it. Other than that..." I finished my tea. "Will, energy, vision, runes, cutie marks, runecasting and artifacts…I think we covered the basics." I grinned. "Does that answer your questions?"

"Huh?" Sweetie gave me a confused stare. "That's all?"

"That's all." I shrugged. "The rest is application, which might be a little much for you. But maybe in a few years, if you want more help, Twilight can give you a little - "

Snnnnerrrk.

“What was that?” I turned my head, searching for the source of the sudden snore.

“Rainbow.” Twilight shrugged.

“She is sleeping here!” I sprang to my feet, pacing around to look for her. I spotted her quickly; she was collapsed messily on a beanbag, behind a shelf, a few rows over. “She promised to meet me at one!”

“She’s been reading all morning.” Sweetie Belle trotted up behind me. Twilight nodded.

“Hmm.” I glanced at the sleeping pegasus. “The rest is application, Sweetie, but maybe a demonstration would help.” A wicked smirk spread across my face. “Twilight, want to help me glue Rainbow Dash to the ceiling, as payback?”

“Hmm.” Twilight glanced at Sweetie, and smiled. “Well. If it’s for learning.”

Rainbow snored on, oblivious, as we exchanged conspiratorial grins.

Addendum

The schools of magic Wesley knows about (not all there are):

Aporiasis - magical discipline that can 'translate' between phenomenotions. (Rune-concepts.) Less useful than it sounds.

Bizzanarchy - magical discipline that re-writes basic laws of reality. The anti-gravity spell falls here.

Iconarcana - magical discipline for passive magic in icons. A specialized type of artifice.

Echonarchy - magic of sound. Lyra uses metamancy to align her intrinsic magic to this school, so she can apply her cutie mark to it.

Somnology - for magics related to sleep and dreaming. One of Luna's specialties.

Numancy - for magics and research related to the soul. Wes is not a fan. Currently on Equestria's 'black' list, due to it's dangerous nature.

Arcanology - the magic of 'spending secrets'. Used for communication, not divining.

Resography - the study of multiple realities. Poorly understood, even more than the rest.

Entropology - spells for heat manipulation. Easy to use, hard to master.

Kinesthism - spells for movement, a superset of telekinesis. Too many contributors to this school means it has blurry boundaries.

Minarchy - a system for allocating degradation and chaos. Helpful for optimizing large systems.

Metamancy - school for magic that affects magic. Lyra is one of the few experts.

Geromancy - Age - related magic. Complex interactions and abstract concepts make this incredibly hard to master.

These aren't schools, exactly, but they may be of interest:

Phenomenotions or Phenomenotation - The concepts used to cast spells or write runes. Can be very abstract.

Thaumotricians - doctors that examine innate magic.

Numismatrix - An arcanology tool. Can be used to exchange a 'known' secret with an 'unknown' one under certain conditions.

Subthaumology - A philosophical study of magic, usually discussing why it does what it does. Tends to be polarized between 'practical' thaumaturgists, who don't care, and 'armchair' magicians, who can't cast anyways... or so the other group says. Comparable to metaphysics.

That's the entirety of the list in my notes. However, I make these up on the spot, so if you find one not listed and want a definition, I'll make one up - ahem, I mean, I'll try and remember what I was thinking.