That was a good question.
Hughes’ understanding of machinery far surpassed this era, yet even on Earth, there were only a few types of industrial fuels.
The first type was solid fuels, coal, firewood, and plant stalks, resources that humanity had used for thousands of years.
Then came petroleum and natural gas, including various alcohols and alkanes, the lifeblood of modern society.
From speeding automobiles to rockets, they all relied on these fuels for combustion.
Beyond that, there was nuclear fission and fusion, from uranium to deuterium, tritium, and helium-3, whose brilliant radiation also signified the radiance of civilization.
So, what exactly counted as mundane fire?
In this world, the term "mundane" naturally contrasted with the supernatural.
This was interesting.
"Are you sure the Mechanical Cathedral has no supernatural pathways and no supernatural beings?"
Chloe pondered for a moment before speaking, "I think you misunderstand the Mechanical Cathedral. It truly has no supernatural pathway, it is not a supernatural organization. But as for supernatural beings, well, there definitely are some."
As she spoke, Chloe rubbed her eyes with one hand, then raised a brass sacred emblem. "I am one."
The surrounding people’s breathing halted in sync with the tremors of the steam pipes. One by one, their gazes fell on Chloe.
Under the firelight of the steam engine, the brass sacred emblem swayed gently, making Hughes’ eye twitch.
"You’re also part of the Mechanical Cathedral?"
He took the emblem from Chloe’s hand and examined it closely.
The brass sacred emblem shimmered with a dark golden ripple across its surface.
Its edges bore engravings of steam gear patterns, between which ran dark red veins of copper rust, resembling biological circuits that writhed under the glow of the boiler fire.
But why did brass have red rust?
No, this wasn’t rust, this was more like bloodstains.
Hughes flipped the brass emblem over.
When tilted at a certain angle, a three-dimensional relief resembling the human brain’s gyri and sulci appeared on its surface.
These parallel lines, originally symbols of reason and order, now seemed eerie and distorted.
As he rotated it, they appeared to writhe slightly.
Hughes felt an extreme contradiction.
From a design perspective, the emblem had a strong industrial aesthetic, clean, precise lines that perfectly matched his taste.
Yet, it was adorned with all sorts of chaotic embellishments, whose colors and shapes were grotesquely twisted, making him feel deeply uncomfortable.
These two completely different styles merged into something indescribably bizarre, like pouring a bottle of strawberry yogurt into a pot of delicious stew.
Both were pleasant separately, yet together, they were simply nauseating.
"I did indeed join the Mechanical Cathedral, though this organization may not be what you imagine," Chloe said as she took back the brass emblem.
"The Mechanical Cathedral isn’t actually its real name. They simply resembled a church so much that, over time, people started calling them that. However, their true name is the Mechanical Society."
A hint of longing appeared in Chloe’s eyes. "It is said that in the beginning, they were just a loose academic organization, purely focused on research. But after the Great Sage Bruno disappeared, the Mechanical Society gradually consolidated its power and stopped sharing knowledge freely."
"Sharing knowledge for free? I thought only your Moths Chasing Fire did that. They shared knowledge too?"
"Of course. They were among the first to do so. When they first sketched the steam engine’s blueprint on a blackboard, Moths Chasing Fire was still just a branch sect of the Candlelight Emblem.”
"During the Great Sage’s time, the Mechanical Society was also a symbol of progress and openness. Who could have expected them to become so extremely conservative now?"
Chloe’s tone unconsciously turned somber. "Back then, Moths Chasing Fire cooperated with them. Every past chief was a member of the Society, and this tradition has been maintained for over a thousand years."
"Unfortunately, we are no longer fellow travelers."
She sounded a little dispirited.
Casually tucking the sacred emblem away, she took a few steps back, lightly biting her lower lip. With arms crossed, she leaned against the doorframe.
The flickering firelight cast long shadows over her nun’s robe.
Though she stood among people, there was a faint sense of solitude about her.
The Mechanical Cathedral had once been an open and inclusive academic organization?
What had they experienced to lead them to the opposite extreme?
A stuffy feeling weighed on his chest.
People in this world had once pursued technological progress just as fervently, only to eventually return to extreme conservatism, as if by some unseen force.
"In any case, I know them well enough. The Mechanical Cathedral is now just a group of ordinary people fanatically worshipping all kinds of machinery.”
"They don’t possess such bizarre steam engines. Their technology generally doesn’t involve the supernatural, at least, not the older ones."
"Doesn’t it involve the supernatural? That phrase ‘steam tolerates no mundane fire’s desecration’ doesn’t quite fit."
"That came later. They gradually became more extreme, their convoluted rules multiplied, their worship of technology became fanatical, yet they strictly forbade interpreting technology.”
"With such a flawed foundation, I wouldn’t be surprised by any absurd conclusions they’ve drawn."
The factory fell silent once more.
From the steam engine’s combustion chamber, the entity pollution continued to strike against the furnace door, making dripping sounds like raindrops hitting the ground.
A timid voice broke the silence.
"I... I have an idea…"
Hughes turned his head, blinking in surprise. "Gaia?"
"Yes, my lord. And Chief… I have an idea that might be worth testing."
Hughes glanced at Chloe beside him.
She leaned in and whispered, "Gaia has joined Moths Chasing Fire. Don’t worry."
That made him even more uneasy.
Gaia was already reckless, and Moths Chasing Fire had a notoriously unreliable reputation.
This wasn’t just a case of one plus one equaling two, it felt more like an exponential disaster.
Maybe he should consider assigning someone else to oversee the explosives production line.
Hughes sighed inwardly.
The last thing he wanted was to wake up one day and find Castel floating in the sky.
Gaia gratefully nodded. "My lord, I think we should test the Mechanical Cathedral’s ritual on another steam engine, one that hasn’t undergone a summoning for a Machine Soul, just a regular steam engine."
Hughes and Chloe exchanged glances, both seeing the surprise in each other’s eyes.
They immediately understood the implication behind Gaia’s words.
"You think the Machine Soul is what caused the Mechanical Cathedral’s ritual to mutate?"