The wisp of immortal essence entered from Lin Mu's chest and created some pressure.
Lin Mu found the Immortal essence to be a lot heavier than Immortal Qi. At the same time, the Immortal essence was vibrant and sent waves of comfort in his body.
'So this is the next level of Vital essence... Immortal Essence...' Lin Mu thought to himself.
The difference between the two was quite vast, despite being in the same category of energy.
Every normal creature in the universe would generate its own Vital Energy. This was something that was part of the natural order, and there were very few exceptions to it.
Only when a creature reached a certain cultivation base or strength, would it naturally start to generate Vital essence. Vital essence was a highly compressed and refined form of Vital Energy and was a lot more difficult to handle.
If a weak body obtained Vital Essence and was unable to contain it, there was a chance that they might just explode. This was also why one needed to strengthen their body a lot before Vital Essence could be used.
But even then, this vital essence would either have to be obtained from external sources or manually refined in one's body. Only when one reached a certain baseline would their body naturally make Vital Essence from the start.
Lin Mu was at this juncture, and all the vital energy in his body would automatically be turned into Vital Essence. All his cells were filled to the brim with it and provided him with great vitality and stamina.
But even if one used Vital Essence to cultivate their body, there was a limit to it. After a certain point, their body would not improve no matter how much vital essence they obtained and there was a chance they would end up harming themselves too.
At this point, one needed to sublimate their Vital Essence to a higher form of energy, which was the Immortal Essence.
But doing so was impossible for a lot of creatures. Only those with special bloodlines or certain types of beasts could do this naturally.
For humans, this was not possible either.
If they wanted to cultivate further, they needed to obtain Immortal essence from external sources and then refine it into their body. This could be obtained from Immortal Essence crystal, special fruits and herbs, as well as by consuming other creatures.
And if a human wanted to naturally generate Immortal Essence, they needed to fulfill several conditions. The main one being an immortal constitution.
Thus, unless one was born with it, they could only acquire one though hard work and cultivation. And this is where the body cultivation techniques came into play.
The Three Apertures Invoking Technique was one such technique that was analogous to Qi cultivation in that it involved the creation of a 'vessel' to store this Immortal Essence.
After all, immortal essence could not be held by body cultivators who did not have an Immortal constitution naturally, thus they created this method.
In the case of Qi cultivation, creatures had Dantians, but in this case one created three Apertures in their body.
The first aperture was at the very top of one's sternum and this was where the first wisp of Immortal essence was supposed to settle.
As Lin Mu followed the mnemonics of the Three Apertures Invoking Technique, he realized just how difficult it was in reality.
~shua~
After a minute of struggle, the wisp of Immortal Essence directly escaped his body before dissipating.
'Seems like I'll need a while to figure this out...' Lin Mu thought to himself.
He repeated the process again, pulling in another wisp of immortal essence into his body.
This time though, he was able to hold it in his body for two minutes before it escaped again.
'So I'll have to first learn how to contain it in my body...' Lin Mu understood.
He repeated the process over and over again, as the holding time for immortal essence continued to extend.
~Crumble~
By the time he was able to hold a wisp of Immortal essence within his body for twenty minutes, the first immortal essence crystal was depleted. It crumbled into dust and floated away with the breeze.
"Thankfully, I bought enough of them." Lin Mu muttered to himself.
He didn't start right away though, instead he mediated for a minute and chanted the Calming Heart sutra.
He continued chanting the sutra under his breath, improving his focus and perception and restarted the process.
~shua~
And right from the start, Lin Mu could feel the difference.
The wisp of immortal essence flowed a lot more smoothly and Lin Mu could also see the path it had taken.
'So there it doesn't just pass through my flesh... it actually passes through certain natural gaps there are present.' Lin Mu realized.
The more he thought about it, the more he grasped.
'Is this due to the fact that my body isn't able to handle the immortal essence directly? Yes... that must be it.' Lin Mu understood. 'Since it cannot enter my flesh and blood, it takes a route that is not occupied by it.' He continued to analyze it, guessing that this might be the key to making his first aperture.
After a couple of hours of work and observing, Lin Mu felt like he had improved.
'Now I see... if I am to open an aperture, it needs to be in a natural 'gap' in my body. And since the instructions say the first aperture is at the top of the sternum, the empty space should be there too. I just need to find it...' Lin Mu progressed steadily.
He knew that even if creatures of the same species were the same, there were bound to be differences between them. The same applied to humans, and no two people were the same. Even in twins, there were differences on a microscopic level.
This was the reason why it was stated that while the first aperture would be at the top of the sternum, one still needed to figure out exactly where it was depending on their own body.
Lin Mu continued to pull in more Immortal essence wisps, and once he reached the point where he could hold it in his body for over an hour, he knew he could move on to the next step.
Lin Mu guided the Wisp of Immortal essence to not just stay within his body, but to actually move around. He needed it to find the right spot where he could let it 'rest'.
Still, this was easier said than done. The scale of navigation was microscopic and if Lin Mu made any mistake, the wisp would simply dissipate. Two days passed like this before Lin Mu finally discovered it.
'There... this should be it...' Within Lin Mu's chest, a wisp of Immortal essence was floating steadily in one place.
There was a wide space around it, unlike the empty gaps it had flowed into the body. Of course, this wide space was only wide compared to the scale of the wisp.
'It is only a few times bigger than the other gaps, but it will do...' Lin Mu decided.
After having found a suitable space, the next step was to actually form the first Aperture.
And to do this, Lin Mu needed more wisps of Immortal essence.
~huu~
"Let's see how it goes..." For the first time, Lin Mu drew in his second wisp of Immortal essence while one was held in his body.
He had to split his attention in two places, with one holding the first wisp in place and the other controlling the second wisp. Thankfully, with Lin Mu's experience with Spirit sense and Immortal sense, it wasn't anything new to him.
Plus, he had spent a decent amount of time finding the right 'path' to his perspective site of aperture and thus didn't make any mistake there, causing the wisp to dissipate.
Soon, the second wisp of immortal essence was also appeared in the empty space.
"There we go... Now to add more..." Lin Mu didn't stop there and pulled in a third wisp.
He successfully managed to bring the third wisp in the empty space and moved onto the fourth one. But on the fourth wisp, he made a mistake, and it ended up touching the 'walls'.
This caused the fourth wisp to be ejected out of his body. Though thankfully he managed to contain the other three wisps of immortal essence.
'At least they won't get disturbed if I make a mistake in pulling a wisp.' Lin Mu felt a bit relieved.
He did not want it to be like the refining of spirit sense, where a single mistake could make the entire tendril of spirit sense collapse, having one to make it again.
Still, Lin Mu learned from his mistake and steadily added more wisps of Immortal essence to the empty space.
Time continued to pass and now, Lin Mu had nearly a hundred wisps of Immortal essence in the empty space!
