Teaching
The standard Dokkaebibul formula used at Daehan Seodang was so massive that it covered half the classroom blackboard.
From the implementation that converted spiritual energy into fire, to maintaining the flame's temperature and shape, down to the control that determined its position and direction of movement.
To create and move six flames at once, one had to draw dozens of formula runes.
"How did you do it?"
"To put it simply, I compressed it."
"So you stepped outside the existing rune system?"
"No. Every character I used was already part of the existing system."
Dohyeon fetched a scroll bearing the standard Dokkaebibul formula from the corner of the room and spread it out.
Then he pointed out, one by one, the sections that repeated in similar shapes.
"Do you know what this part, from here to here, does?"
"It converts spiritual energy into fire and maintains the flame's form."
"And yet when you make six flames, doesn't this all repeat in roughly the same way?"
"...But aren't the positions different?"
Seo Yu-ri answered timidly, pointing at each formula rune with her finger.
"Only the position and direction change, right?"
"Which means it's a different formula each time."
Feeling like the conversation was running on parallel tracks, Dohyeon fell silent.
Seo Yu-ri wasn't wrong.
To the Taoists of this world, a formula was a single, completed painting.
When a grandmaster-level Taoist finished a formula through intuition and trial and error, the spellcasters of later generations simply memorized it as it was. Even when new spells were created, it was usually just a matter of cutting out the needed pieces of an existing formula and stitching them together.
People knew how to draw the picture, but few ever asked why it had to be drawn that way.
Because of that, a formula with a single line changed was considered a different formula, and shifting even one rune that designated a position was treated as an entirely new spell.
To Dohyeon, on the other hand, a formula was not a painting.
It was a collection of statements that took inputs and produced defined results.
Each rune was a single function, and the outcome depended entirely on the order in which those functions were connected.
To Dohyeon—who in his previous life had spent countless hours tearing apart and rewriting code—a Dokkaebibul formula that laid out the same structure six times over was inefficiency incarnate.
Dohyeon pointed a hand at the six nearly identical runes on the scroll.
"You see this entire thing as one formula, don't you?"
"Of course. It's all connected."
"I see it differently."
Dohyeon spoke slowly as he used his brush to divide the scroll into regions.
"This is a structure where several small formulas are linked together to produce a single result. Looking at the big picture, there's a separate part that creates the flame, a part that maintains its form, and a part that determines its position."
"Yes."
"So what I did was create a function that produces one Dokkaebibul, and then pass in temperature, form, and position as parameters."
"Uh... a function?"
Ah. He'd slipped.
The word rolled naturally off Dohyeon's tongue, but it was a concept that didn't exist in this world.
Perhaps because Taoist magic held sway here, science and mathematics lagged considerably behind his previous life.
Not that the technology itself was primitive.
From heating devices that burned spirit stones for warmth, to transport tools that carried heavy cargo, to transmission devices that carried voices across vast distances.
Formulas were doing the work that machines had done in his old world.
The direction of development was simply different.
Since products were built on spirit stones and formulas from the ground up, and society itself ran on that foundation, there was never any pressing need for scientific advancement.
When a brilliant Taoist produced a new formula through feel and repeated experimentation, the spellcasters who came after memorized it wholesale rather than analyzing it.
As a result, the arrangement and connection of runes differed from school to school and family to family.
'At first, every formula used its own grammar and structure, and reading them was a real slog.'
Another problem was that any formula of 4th tier or above was treated as a family's closely guarded secret.
High-tier formulas were never compared or improved upon even when newly developed. To do so, it was said, would be passing the family's power into foreign hands.
In the end, aside from the truly basic rune system, no common grammar existed at all.
Dohyeon explained again to Seo Yu-ri, who was staring at him blankly.
"To put it simply, I built a mold."
"Ah! A mold for stamping out Dokkaebibul!"
"Exactly. Once it's made, you just stamp it six times."
"Wow, if you do it that way, you really only need to draw a fraction of the formula."
Aigoo, if she's this floored by a simple grammar system, how is she going to handle the concept of AI later?
There was a mountain of formulas he needed to experiment on, and only 2nd-Rank spiritual energy to work with.
Looks like I've got no choice but to find a way to increase my mana reserves.
"It's not just about making things shorter, either."
Dohyeon traced the tangle of connecting lines drawn across the scroll.
"By omitting the unnecessary runes and connectors, you eliminate the inherent leakage, collisions, and redundant computation that occur along the path the spiritual energy travels."
It wasn't simply the size of a formula that determined how much spiritual energy it consumed.
In the end, what decided it was how large a demand the spell placed upon nature.
But when a formula stretched out, spiritual energy inevitably leaked or collided and evaporated as it traveled along the formula's lines.
Energy vanishing beyond the cost of making the demand on nature itself.
That cost was precisely what Dohyeon had eliminated.
"So the spiritual energy required to create the flame itself doesn't decrease, then."
"That's right. The cost of bending reality stays exactly the same."
"And yet it uses overwhelmingly less energy overall?"
"Yes. Most formulas used in the current Taoist world are built inefficiently."
Seo Yu-ri gazed at the dense web of connecting lines on the scroll.
Having heard Dohyeon's explanation, the lines that had once looked beautiful to her were beginning to look like clutter.
'All this time, I was taught that a formula was a work of art created by Taoists.'
They said the beauty of a formula lay in its completed form.
Remove even a single line and the harmony collapsed; change even one rune and it stopped working—so don't even think about touching it.
"All right then, study this and come back by the end of next week."
Dohyeon handed a small booklet to Seo Yu-ri, who was staring at the formula with a stunned expression.
She carefully opened the first page.
The runes were familiar, but the symbols and their order were not.
A way of grouping repeated runes into a single block.
A way of passing specific information in from outside.
This was the new formula grammar Dohyeon had compiled based on the coding knowledge of his previous life.
"What is all of this?"
"The foundational grammar of the formulas I use."
"This is foundational?"
Seo Yu-ri said, gauging the thickness of the booklet between her fingers.
"Hmm. I never expected to be teaching anyone, so I haven't organized anything beyond this."
"If I master this, can I use formulas the way you do, Sabu?"
"...Sabu?"
"Yes, you're my Sabu, after all."
"Well, call me whatever you like. This is only the foundation, of course. But even mastering just this will cut your energy consumption down considerably."
Seo Yu-ri's face hardened with resolve.
After all, what had been the reason she'd been discriminated against, the reason she'd never earned proper grades?
Wasn't it simply that she'd been born to an ordinary family, missed the window for mana adaptation training, and therefore carried only a small reserve of spiritual energy?
Her innate talent and intuition were brilliant enough to earn her admission through the Equal Opportunity Program.
'If she had this too, she might even win an excellence scholarship.'
Aside from her mana reserves, Dohyeon had never once considered that she was inferior to anyone.
When he imagined Seo Yu-ri mastering everything he taught her and getting revenge on the senior disciples and students who had looked down on her, it tasted impossibly sweet.
"Even if it kills me, I'll have this mastered perfectly by the end of next week!"
"No, that's— you really don't have to go that far."
"See you next week, Sabu!"
Seo Yu-ri whirled around without giving Dohyeon a chance to respond.
The sight of her sprinting out of the warehouse, clutching the small booklet tight to her chest, was somehow stirring.
Dohyeon watched her back grow smaller through the open door.
"So green it hurts."
He'd sworn off studying for good in this life, and yet he was the man who had voluntarily walked into the hell called graduate school in his previous one.
He had a fundamental appetite for inquiry and scholarship, and this life had been getting a little boring—when along came a newbie who practically walked into his lap on her own.
The thought that if he taught her all the grammar he'd built, they might end up researching formulas together began to excite him.
"Eek, I have to go."
Getting swept up in Seo Yu-ri, two hours had slipped past before he knew it.
Hm, I wonder if old Man Manbok is still waiting for his drink?
Two days later.
From Monday morning, the front courtyard of Soeun Academy was packed with students.
"Move faster! You planning to depart after the sun's already at its peak?"
Dohyeon gritted his teeth as he hauled a cart piled with cargo taller than a man.
Portable tents and emergency talismans.
Storage cases for monster byproducts, plus cushions for the students to rest on.
It was everything prepared for the students' field lesson observing the demonic realm.
"All this over a single drink, eh."
Originally, Dohyeon hadn't been on the roster for this observation trip.
He'd gone on the last one, so this time it was his turn to rest.
"Ahem, what's this sour talk, eh? I put you down because you're young and sturdy—trusted you with it, I did."
He'd been dragged out because Jang Man-bok, who'd caught a stomach bug, had quietly added his own name to the vacant slot left behind.
Still buried in managing the supplies, the head laborer came over to Dohyeon.
"Dohyeon, you're on Team 7. You know the supplies list? Pack it all up nice, follow the Team 7 students there and back, and that's that."
"Yes, sir."
"They'll be organizing the teams over there."
Within the demonic realm, the laborers' job was to shadow the students, distributing emergency talismans, rations, and spare tools, and to store the byproducts harvested from the monsters.
Dohyeon gathered the necessary supplies, stuffed them all into an enormous backpack, and slung it over his shoulders.
By then, the Soeun Academy students, their teams apparently all sorted, had begun gathering in the center.
Most of them clustered in groups of three or four.
Students from the same family.
Students who were already friends.
When he went looking for the Team 7 sign, he spotted a familiar face among the three students there.
A small frame, hair tied neatly back.
It was Seo Yu-ri.
"I'm the laborer assigned to Team 7. Looking forward to working with you."
At his words, the students all raised their heads at once.
Dohyeon's and Seo Yu-ri's eyes met dead-on.
"......"
Seo Yu-ri's eyes went wide, and her lips slowly parted.
"Sa..."