What was the easiest, simplest, most basic representation of 'Knowledge' that came to mind? For Eiro, it was a book.
Books were collections of knowledge, that which brought it to others, and that what brought it to Eiro in the past, and will continue to do so in the future. So, all of Eiro's knowledge was to be gathered within a single book in his mind to represent the ability .
The memories that were missing were pages that had been ripped out or dirtied so that you weren't able to get the information from that page anymore. But no matter what Eiro tried, he wasn't able to properly make use of this book in the right way.
He flipped it open, and he wasn't able to connect to his memories through it. He was able to read a few things within there, sure, but it was information that he 'wrote down' on his own. Eiro was supposed to fill all of the information in automatically by linking his ability with this mental image. However, it was more like he was somehow trying to make it seem like it worked. The 'broken memories' that were shown in the form of the ripped up or dirty pages were just randomly scattered around in the book instead of being truly representative of the time in the Demon's life.
But maybe that was just the issue? Was Eiro's whole life able to fit into a single book? Sure, he had the grimoire that was basically infinitely long somehow, but that wasn't a normal thing that books were able to do.
No normal book could explain every small detail and every small bit of information that Eiro saw and took in within his whole life, especially considering the depth of information that he had been experiencing ever since he became the owner of the Five of Pentacles.
The Demon stared at the book in his mind, trying to see what would happen if he chose to take multiple books. Maybe have a book per year? Or maybe a book for every year? The book for the past year would be quite a bit thicker than the others, though. Not only because Eiro's perception increased by so much, but also because he experienced so many new things, and learned so many new things as well.
Then maybe he could just split it up by category? He could take out the books that he read in the past, that were a definite part of his memory, and put them away. Then maybe he could take episodic memories, the memories of things that actually happened, and turn them into something like... diaries? Or 'novels', maybe. Splitting them up into smaller packages.
Then, all of Eiro's direct knowledge, the raw information that he knew and took in could maybe also be something separate. But if he did that... Then couldn't he create a whole library? Sure, it was more complex than the simple book, but it still wasn't anything too outlandishly complicated. Libraries were simple things as well. All the information was sorted, and it obviously could hold a lot more information than just a single book.
He could add Grimoires, Beastiaries, and the hundreds of regular books that he read in the past into there. And the parts of his memories that were missing could be represented as nearly broken-down books, or simply gaps in the shelves that were otherwise filled to the brim. It seemed like this sort of thing would be a better representation than just a book, even though it was obviously more complex.
Maybe that's what Lognir meant when he said that he was supposed to create an image that was 'Simple', and not 'Easy'. It would be easier to have a single book, having everythingg compiled into a singular item, but it would maybe be simpler, although not easier, to have a large space instead.
Sorting through a book like that would take a lot of time instead of going through a library with hundreds of well-sorted books depending on themes and topics that he could traverse instantly. The Demon figured that this image was the best he could choose, and he felt a lot more connected to it anyway.
He felt calm and collected whenever he found himself in libraries, which was exactly what he needed for this sort of thing.
Eiro saw himself standing in this library. He looked around, as if he was sorting books into this space, he went through his memories bit by bit and turned them into books in front of him. Whenever a book was complete, it was placed into the right area.
It was easier to connect this library with his skill than it was when the image he chose was a simple book. Eiro looked around and inspected the different parts of this space around him. Without him having to actively sort through things now, books were simply automatically appearing in the air and sorting themselves into the right shelf.
They shifted around properly, and soon, it became apparent which ones were the ones that held Eiro's broken, or missing memories. Compared to the high-quality, neat, and tidy books that were seen everywhere else, these were books that were thrown to the streets and trampled on for multiple years. It was as if they were a shell of their former self.
Soon, nothing more was happening. There was a single book laying on something of a pedestal that had text currently being written in it. It was the book of what was happening to Eiro right now. His thoughts and emotions were being noted down there all at once. But otherwise, nothing else happened. This library was 'finished' for now, all his memories were properly categorized.
Eiro walked to one of the shelves and pulled out a random one of the books. It was about one of Eiro's trips to the city near where they used to live to get a few supplies. He flipped it open and looked at the pages. As he read, he slowly but surely became immersed in the moment and was able to see the memory as he normally saw them. Once the memory was over, Eiro held the closed book in his hands, and was able to place it back into the shelf.
"So it works..." The Demon muttered quietly, smiling softly as he continued walking around this library to look for one of the broken books. Soon, he saw it. It seemed like it would be uncomfortable just holding it in his hands, and it was as if his whole body was rejecting it as he placed his hands around the books spine to pull it out of the shelf.
When he opened the book up, there certainly were a few letters there, but they were covered in word-scrambles covering them up, making it impossible for Eiro to read or decypher them. Some other pages were ripped up or missing altogether... This really did seem a lot like Eiro's memories.
There were some that he didn't have access to at all, and others were kind of there but no matter how much he tried to remember them, it was as if there was a wall in front of him that he was experiencing them through.
Slowly, Eiro took a deep breath and grabbed the book, slowly bringing it over to one of the desks that he made as part of this library, since it had to be realistic of course, and sat down at it. He imagined holding a pen and having a second, empty, book in front of him.
Eiro squinted his eyes and looked at the first page of the book. It was hard to see everything, but he was able to slowly remove some of the layers on top of the letters in his mind to decypher what was truly written there. And using that, he could rewrite the book of this specific memory. This book was a lost cause when it came to repairing it. That would just not be a possibility. But instead, rewriting it should be something he was able to do, so he tried his hand at it.
And as he was doing so, rewriting the parts of the book that were actually left for him to read, he was able to slowly remember things that he had completely forgotten. The 'walls' on this memory were slowly disappearing. It was a memory of an afternoon that he spent being taught by Jura. It was a precious memory, of which there were hundreds that were nearly completely the same, but it was still important to Eiro nonetheless.
The Demon continued noting down everything that he was able to decypher in this book, until all that was left were the parts that were directly missing.
"...What am I supposed to do with this..?" Eiro muttered quietly out loud, and Lognir looked at him with a curious smile, "Is everything alright?" He asked.
Eiro slowly opened his eyes and nodded his head, "Yes... It's slowly working." Eiro started. Then, he went on to explain the image that he chose and that it seemed to be working pretty well for him for now, with the exception of those missing pieces.
"Well, they have to be somewhere within that library then. It seems that you have heard this before, but what was once there can never be truly lost. It will just be hidden, or somewhere else. But nothing can ever disappear without coming back in some form or another." Lognir explained, and Eiro looked down at the ground in thought.
And then, Lognir said something else, "Do you know why Solomon sent you here to me?"
"...Because you're the only one that he knew of that had these abilities? The... ability to manipulate abilities?" Eiro asked, and the Dragon lightly shrugged, "That may be part of it, of course. But the main reason is because of your card. The . I possess a similar force within myself naturally. With it, you will be able to find that which is missing with relative ease, if you know what you're doing at least. That's why you were sent here. So that I could help you find the 'true location' of that which you are missing. Or it should be something like that, I'd assume. Solomon didn't explain too much to me, really."
"The true location... So... They are hidden in my mind... Where would you be able to hide something like that in a library..?" Eiro asked himself quietly, before something popped into his mind. Something that seemed to make some sense to him.
"I got it..." The Demon muttered. He went back into the library in his mind and searched around, before finding something that was a bit amiss. One of the floorboards had a slight crack. Eiro knelt down and pulled it up, revealing the pieces of paper that have been crumbled up and stuffed in there. His missing memories. Dirty, the text covered up by mud and not even close to all of them... but a handful of them they were there. And Eiro would be able to use them to remember some of the things he forgot.