「Old memories from Luz.」

After a few of the children awakened, the old man continued his lectures.

"Gramps, what will you explain today?" asked Luz with a yawn as the village elder called all the kids.

"Well, I want to explain mana to you all since we couldn't finish it yesterday. Also, I want to show you a few experiments to deepen your understanding of those laws," explained the elder casually to a group of children.

Unlike their last lesson, this time the children remained well behaved. The reason is simple. They feared the old man's cane since he didn't shy away from using it.

Seeing these kids being well behaved, the elder introduced the kids to the phenomena of entropy and diffusion.

Upon the elder's call, two villagers walked up to him. The first one bought a heated cup of water before putting it inside a colder container, while the second person carried a glass cup and two different liquids.

The elder nodded in acknowledgment before starting the lecture."Before we can begin, I must explain the two phenomena of entropy and diffusion."

While pointing towards the container, the elder continued: "So let's start with the phenomena of entropy. All of you are familiar with that phenomenon. If you leave a cup outside in the cold, it will cool down till it reaches the ambient temperature. But what you don't know is that the environment absorbs the heat and the ambient temperature rises slightly, even though it's negligible."

The children didn't seem to be surprised. Instead, their facial expressions seemed to ask: "Do you think we are stupid??"

Seeing that, the village elder sighed: "At least act like you are surprised. This old man uses his precious free time to introduce you, brats, to some concepts."

The children giggled, and the old man began introducing the second phenomenon while mixing two different fluids in a glass cup.

"If you introduce two different gases or fluids into a container, these two will mix completely," stated the old man.

The kids didn't look surprised, and one of them immediately asked: "what about oil and water."

"Well, you got me. We shall ignore them for the time being," commented the elder before asking the kids: "Why am I even telling you that? Well, it's simple, mana also obeys these two phenomena."

Before the old man could continue, Luz interrupted him with a question."But I thought mana is something pure like water!?

The old man nodded before explaining the situation to them. "Unlike what people might believe, mana from the environment isn't pure and is filled with elemental impurities. These impurities have their uses, but let's ignore them since it would go too much into depth. To keep it short: mana is like crude oil that can be refined to its elemental components."

[Author note: Yeah, I know that these pesky villagers have no clue about crude oil, but his explanation is meant for you, so it doesn't really matter].

The explanation, however, only confused the children as more questions arose than answers. What are those impurities, and are there any use cases for them? What happens if one refines mana?

The elder merely smiled before he continued with his explanation. "You don't have to worry about those elemental residues since your mana core is responsible for refining and disposing of them."

The lecture continued, and before it ended, a person asked the elder: "So, why are we supposed to train our physical bodies if we will fight with magic in the future?"

The elder had asked himself the same question in their age back then and smiled out of nostalgia before answering it with a question. "Well, as I stated earlier, your body refines mana, so in the end, the mana in your body is purer compared to the environment. Shouldn't the mana from your body escape into the environment till it reaches equilibrium?"

The kids nodded in confusion and pondered the former's question. If entropy and laws of diffusion also work on mana, how come we can hold refined mana.

"The refined mana will always escape your body. But the stronger your body is, the slower the dissipation will be," answered the elder before ending the lesson. ***********************************************************************************************************************************

Author note: Well, unfortunally, we can't continue without another info dump about parasites.

As you all know from biology class, an animal is considered a parasite if it needs a host to survive and reproduce. Some parasites in this world are known as hive parasites. Hive parasites have negligible individual IQ and heavily rely on their hive IQ, unlike humans.

Think of these parasites as if they were neurons. Alone they are stupid, but the moment the neurons interconnect with each other, they can form a brain (heavily exaggerated). Just like neurons, these parasites communicate with each other via impulses and hormones.

The parasite used in Luz's case is known for its high reproduction rate, adaptability to changes in the environment and the host, and small size.

Like any other creature on this planet, it has a mana core. But unlike others, their mana cores are way too weak to absorb mana from the environment, and it gets worse. They are not only unable to absorb mana from the environment, but they also can't even accumulate it due to their weak bodies. This limits any potential natural magic evolution and forces them to rely on a host.

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「Back to reality」

In Luz's body, however, the parasites drilled in and multiplied rapidly via asexual reproduction until there was at least one parasite in almost every cell of Luz.

They greedily absorbed Luz's all the nutrition and mana from Luz's body to fuel their growth. If it wasn't for Simon allowing mana and nutrition to flow into Luz's body, the host would already be dead.

Simon cautiously stood next to Luz, monitoring his body health. Slowly he reduced the number of nutritions and mana flowing into the latter's body at regular intervals.

This forced the parasites to reduce their reproduction and consumption to sustainable levels as they couldn't change hosts in the foreseeable future. For the well-being of the parasite collective, the host Luz had to survive since they would perish with their host.

The hivemind paused its invasion near the host's brain as they couldn't take the risk of premature brain death due to the bursting of synapsis. But unfortunally for Luz, a few parasites bore right through the crack in his mana core, as the mana concentration there was the highest.