"During the body refinement phase, we have to place the accent on speed. Regardless of the size of the core back then, the effects of filling it were identical. Which meant that having a bigger one didn't matter and so, it was better to have the smallest one possible. That is why you built a pyramid. Now, however, the goal is different. The focus is no longer on the speed, neither on the body, but on the spiritual energy itself"

"A sphere is the most perfect shape to do so. After many trials and errors, our ancestors piqued this form. There are many advantages to it. For one thing, it is the most balanced of all forms. From whichever point of view, it remains the same"

Jin understood the importance of the pyramid during the refinement stage. That was a basic he had learnt. He could leave it aside. Now, the sphere... It couldn't simply be due to aesthetics? He asked: "That can't be the only benefit, right?"

"Of course not! The best advantage of it is that it is compatible with almost all soul techniques and it has the greatest defensive properties. Regarding the techniques, you will only start to learn them after reaching the 30th stage or so, I won't go into details now but keep it in mind. As for the defensive properties, it is due to it being balanced. Regardless of from where an opponent tries to attack your core, he will encounter the same toughness allover"

"But those are benefits for later. What matters the most is that this toughness is helpful to breaking through the next layers. In order to solidify itself, you have pushed spiritual energy into your core. What if you had pushed too much? Wouldn't it have broken? Or cracked at least? With the sphere, the risks are lowered. Because it redirects equally the force! That is the true worth of the sphere! Do you understand?"

Jin agreed with a nod. It wasn't too complex. It was harder to break a sphere compared to another geometrical form simply because the sphere could redirect the force equally over itself. But that did not mean it was the best to Jin. What about quantity after all?

"Master, what about the quantity of spiritual energy?"

"Good question. You should be aware that every realm induces not only a quantitative change but also a qualitative one, right? Our ancestors had to think of a way that would let us move forward the fastest and the safest while granting us a strength high enough in our realm that we wouldn't be trashed by anyone"

"Now, you understood that the sphere was the safest. What about fastest? That would have been another pyramid. As for the strongest? Well, the bigger you build it, the more energy it can store. But are both worth it? No! Because their advantage is underwhelming compared to their disadvantages. Remember that a cultivator strives for the highest realm. A faster core would make progression easier, true, but would it be able to resist long enough?"

"Every ten stages, you will face a tribulation. With a pyramid core, you will never go beyond the 40th stage. Never!"

"As for building the biggest core you can? You wouldn't be able to reach the 40th stage for another reason: resources!"

"So, what do you think is the best? It is to pick the safest. The sphere will hold against all tribulations as long as you build it correctly. Regarding speed, it is correct, enough that you can reach the peak in theory. It's been proven too... And quantity/quality-wise? It can hold enough energy so that you won't feel at a loss facing someone of your realm. Of course, mostly everyone uses a sphere core build nowadays so it helps"

It did make sense. Without a safe approach, who cared if you were the fastest or the strongest? You would lose in the end. At that time, Jin couldn't help but recall a little story from his old life. The turtle and the hare, was it? Something like that. Anyways, they had a race. The hare being far faster took it easy and lazed about. In the end, he lost to the turtle who moved forward tirelessly, little by little.

What mattered in cultivation? Not the early stages. Not the middle stages either. Not even the latter stages. It was the end. The furthest you could go was what mattered. Taking it steady would win him the race. As an expert in martial arts, Jin believed in effort and continual training. The approach described by Hae-Hyuk was very sound and to him, it was perfectly suitable for the long run.

He didn't find any reasons to nitpick. A sphere it would be! And now, he had to ask about how to make a sphere with triangles. There is no way you can build a perfect sphere with triangles.

"How do you build it with triangles?"

"How? Just bend the triangles"

Wow.

He never thought about this. But it was true. He wasn't working in 2D but 3D. Why couldn't he bend the triangles?

Hae-Hyuk never expected such a dumb question so he was quite taken aback. Even more so as he saw the look of reverence in his disciple's eyes. Just how stupid was this kid? Maybe he had to demonstrate? It would be quite bad if the kid made some kind of mistake on such a part. He would probably die of shame if it was known that one of his disciples built a sphere core without bending the triangles...

He took out a piece of wood and, using spiritual energy, turned it into a perfect sphere. He held it in front of Jin and activated his spiritual energy to show lines upon it. The lines crisscrossed around the sphere forming dozens of triangles, perfectly illustrating how to build the core.

Looking at his disciple who seemed to have understood, Hae-Hyuk heaved a sigh of relief. He promised himself to show the same trick to Min-Su when it was his turn, just in case...