"I require a type of driving force. It has to be said that some remarkable figures have appeared in the west during this past century. For example, right after I left, a man by the name of Isaac Newton appeared. I was almost convinced that he was the reincarnation of a certain death god, but unfortunately, that was not the case. He invented a concept known as force, which I think is very interesting, so I took the concept and invented a branch of force known as driving force, which is something that I need right now. Gui Xu is far too massive, and even though I'm doing everything in my power to support it, I'm struggling to keep up with the costs of keeping it running. However, I'm unable to let it go. Gui Xu is my dream, the guide that brought me into contact with this mysterious world. It is the only pursuit that I've had in this long life of mine. In order to get what I want, I had to display some of my expertise in different fields, and sure enough, I won many plaudits and received a lot of attention very quickly. As a result, I was able to enter the best workshop at the time, Edison's workshop. My teacher is Thomas Edison."

At this point, Qin Ye's grip had tightened so much that he was on the verge of scrunching the entire piece of paper. This was because a certain person had sprung up in his mind, one that was renowned across the entire world.

He was one of the five likeliest candidates in history to have been a transmigrator. Of course, Leonardo da Vinci was also on that list. If those two were the same person, then that would make a lot of sense.

He continued to read the notes.

"During the 100 years that I've been absent, a new type of energy resource known as electricity has appeared. At this point, the foolish mortals clearly haven't realized just how widely applicable a new energy resource was. Perhaps those high and mighty Emissaries of Hell would be able to understand, but they are unable to interfere with scientific developments in the mortal realm. They don't understand, but I do! As far back as 500 years ago, I had already begun searching for a new energy resource that can replace manual labor. Steam power has been invented since then, but that's still not enough! Now, there is electricity, an energy resource that is far more convenient and efficient than steam power! This discovery alone justifies my decision to come here!"

Qin Ye's heart began to thump violently. The name of the figure that had sprung up in his mind was becoming clearer and clearer, yet he still didn't want to believe it.

"I began to research electricity obsessively. Direct electric current has already been conquered, so I chose to participate in a project involving alternating current. It has to be said that this was a stroke of genius! Even I have to praise myself for my foresight. As it turns out, alternating current is an applicable concept, and it's especially useful in electric conduction. In order to power Gui Xu, electric conduction over a massive area has to be achieved, so this is perfect! At this point, my work for this lifetime is basically done, and I've begun to fade from the public eye. Gui Xu has taken me to the Pacific Ocean, and I've begun research into incorporating alternating current electricity into Gui Xu's body. However, I've discovered a problem. Gui Xu's body is not suitable for electrical conduction. In other words, electric currents can't travel through its body. It's a dead creature, and dead things are unable to conduct electricity!"

At the end, the handwriting had become very messy and erratic, clearly indicating that Xu Fu had been furious at the time.

Of course, anyone would be angry if something that they had studied for decades couldn't be used on their most prized masterpiece. The note concluded here, and the rest of the sheet of paper had been incinerated.

Qin Ye immediately flipped the piece of paper over, but there was nothing on the back, either. He immediately picked up the next page. Thankfully, this page was the direct sequel to the last page.

"In order to store electricity in Gui Xu's body, I have to consider not just the mortal realm, but also the underworld. This is an idea that has occurred to me after I calmed down. Thus, I began to trace the development of electricity in the mortal realm, identifying potential misconceptions and unexplored paths to pursue. I've begun searching for items with extremely high Yin energy content in secret, and at the same time, I've enlisted the assistance of my fellow freemasons. After 200 years, I've finally discovered that it's feasible after all!"

The handwriting at the end had become a little erratic yet again, but this time, it was reflecting a sense of excitement rather than anger.

"It's not impossible to set up an electricity network within Gui Xu's body. However, a conversion process is required, and the energy resource used won't be electricity. To put it more accurately, it won't be pure electricity."

Qin Ye's mouth gaped open slightly, and he was already unable to describe what he was currently feeling.

What Xu Fu was trying to do was something that Hell had been trying to accomplish all along!

In the field of instant communication, the underworld had already been completely left behind by the mortal realm. The Usonian Underworld had Thomas Edison, yet it was unable to find a solution. The Argosian Underworld had Archimedes, yet it was also unable to find a solution. Who would've thought that an immortal who had accumulated over 2,000 years of knowledge would also be researching this field?

Xu Fu was only doing this in order to achieve a goal he had set for himself and to give his immortal life some purpose. However, for an underworld, a new energy resource would be revolutionary, and any underworld that obtained such a thing would be sure to reign supreme on the international stage!

Has he succeeded? If so, are there any records?

If the Cathayan Underworld could obtain the method to create this new energy resource, then it wouldn't be an issue at all to catch up to or even exceed the three pillars!

However, this was where the notes on this page concluded. Qin Ye cursed internally, and he was praying in his heart that there would be a follow-up to this diary entry. In contrast with this information, even Xu Fu's identity in this lifetime completely paled into insignificance.

The next page of notes was mostly damaged, but thankfully, the bits and pieces that remained were still cohesive.

"Heart of a death god... Conversion... After removing all of the... Filled with even more power! That's right, this driving force... Omnipresent in both the mortal realm and the underworld... I'm making a record here, the first person to have... Is me! My name is Leonardo da Vinci, I am Emperor Jimmu... Nikola Tesla..."

Many parts were missing from the notes, but it was still able to be comprehended.

Just these short few segments were enough to stun Qin Ye to the core, and he was completely rooted to the spot.

He succeeded? The problem that had stumped all of the underworlds and even his teacher, Thomas Edison himself, was solved by him?

A wry smile appeared on Qin Ye's face. "I suppose it's no surprise. He's accumulated knowledge from both the underworld and the mortal realm, allowing him to connect the two with ease. In contrast, Archimedes hasn't had anywhere enough time as him to accumulate knowledge in the mortal realm, and Thomas Edison's experiences in both the mortal realm and the underworld combined can't even hold a candle to his experiences. If there's anyone in this world that can actually complete this grand project, then it can most likely only be him."

Qin Ye took a deep breath to calm himself down before quickly getting back to the notes.

He was extremely eager to see Xu Fu's solution.

There was no guarantee that Xu Fu's solution could work. In fact, there was a very good chance that it wouldn't be feasible for the underworld. However, it could advance research into a new energy resource in the underworld significantly, and if he could get his hands on that information, the next era of the underworlds would belong to Hell!

However, the solution wasn't in this diary entry.

Qin Ye put down the sheet of paper before quickly going through the rest of the notes, searching for the name "Nikola Tesla". However, his search was proving to be completely fruitless.

Even after flicking through all of the diary entries, he discovered no detailed records, only sporadic mentions of the subject.

Qin Ye was quite disappointed by this, but he wasn't all that surprised. After all, who would write something so important in their diary? The fact that Qi Nü was able to collect these diary entries in secret was a clear indication that they were no longer important to Xu Fu.

"Who could've possibly imagined that Nikola Tesla, Leonardo da Vinci, and Emperor Jimmu were the same person? All of them were reincarnations of Xu Fu!"

Qin Ye had already anticipated that Xu Fu could've left his mark in other parts of the world during his 2,000 years on this earth, but never did he think that every mark that he left behind would be so significant and astonishing.

Nikola Tesla was a brilliant scientist, and the contributions that he made toward the new energy resource that was electricity exceeded even those made by his teacher, Thomas Edison.

He invented wireless power transfer, allowing electricity to be transferred tens of thousands of kilometers away. Through this method, not only could electricity be transferred in massive quantities, it could be released at any designated point in the world. At a time when no one had thought it to be possible, he was able to switch on a lightbulb from a short distance away.

That didn't sound all that impressive until you took into account the fact that only in 2007, after 100 years had passed, did the research team at the Massachusetts Institute of Technology use magnetic resonance to achieve wireless power transfer, thereby successfully switching on a 60 watt light bulb two meters away. The furthest distance that electricity had been transferred over using this method was no more than 2.7 meters, and one of the big selling points of the Iphone X was Qi-enabled wireless charging, but this was something that Tesla had already conceptualized over 100 years ago.

Furthermore, he had also created ultra-high voltage electricity. Using the vastly renowned Tesla Coil, he was able to generate ultra-high voltage electricity of at least twenty thousand volts and as high as a hundred million volts. To this day, over 100 years later, ultra-high voltage power transmission was still a cutting-edge technology that was yet to reach maturity. Currently, the largest indoor electricity generator in the world was situated in the Paris branch of the Électricité de France, but it was only able to generate stable electricity of up to six million volts. To this very day, humans are still struggling to generate electricity in the millions of volts.

In addition to that, there were man-made earthquakes, ball lightning, the dynamic theory of gravity... Nikola Tesla had no less than 100 spectacular inventions credited to his name, pointing out the future path for the human race to take. What was most perplexing about his legacy was that he had relinquished the patent rights to alternating current electricity, thereby allowing it to become a free resource to the human race for the rest of eternity. In doing so, he gave up the opportunity to become the richest man in the world.

Why had he done that? Qin Ye understood why now.

Those achievements were already enough for Xu Fu in that lifetime. He had no interest in accumulating the wealth that mortals were so obsessed over. Having done all he had set out to do in that lifetime, it was time for him to fade into obscurity. In order to commemorate him, a car brand had been named after him, and it was the renowned Tesla brand.

His name had well and truly been immortalized in history.

Some things that seemed to be impossible, such as man-made earthquakes and ball lightning, became almost mundane to Qin Ye after discovering the true identity of Nikola Tesla. Other strange details, such as his refusal to find a spouse and the relinquishing of the patent rights over alternating current electricity, also made sense now.

Qin Ye couldn't help but heave a long sigh. "Who would've thought that my trip to Mirage City would bring me so many stunning revelations."

An energy resource that could exist in both the underworld and the mortal realm... Just the mere thought of this made him want to capture Xu Fu right away! He definitely couldn't allow something like this to be leaked to anyone else!

He had to return to the mortal realm right away and do everything in his power to uncover the truth behind the Peach Blossom Spring!

Initially, he had only been feeling the fury of a ruler whose reign was being threatened, but now, he was full of excitement. This was an opportunity for a meteoric resurgence for the Cathayan Underworld, and it was not an opportunity to be missed!

"Qi Nü, as the core of Gui Xu, you should be able to control it, right?" Qin Ye asked.

Qi Nü hesitated momentarily before nodding in response.

"I'm leaving this place right now, and I'm taking you with me. However, before that, there's something that I have to do." Qin Ye swept a fervent gaze across his surroundings as he spoke. "Activate Gui Xu! I want to see its internal workings, and I want to see this so-called new energy resource in action!"

Qi Nü hesitated for a moment longer before kowtowing and flying away as a streak of light, rushing directly into the ground.

Qin Ye was about to bear witness to a historic moment, and he could barely repress his own excitement. He took a deep breath to calm himself, then began to carefully inspect his surroundings.

Looking out from here, he could see the simulated sea and sky within Gui Xu's body. He waited patiently for about 10 minutes when all of a sudden, a crack rang out overhead.

Countless specks of starlight rose up over the immortal mountain, and a pristine moon also appeared in the sky, giving off a gentle radiance in the sky above. As for Gui Xu, it began to open up in all directions as if it were a gargantuan mechanical contraption, revealing a side to it that no one had ever seen before.

The sky had opened up.