Mr. Pierre-Simon Laplace has been in the library lately, busy with the classification and indexing of books.

He abandoned the original principle of categorization by publication and chronology, and opted for the method of grouping all books into the same or similar disciplines and fields. Put together the books of philosophy, all the literature of history, and all the research materials of the natural sciences...... And within each category, there are many sub-categories. History, for example, is divided and ranked according to different countries and eras.

When dealing with literary works, he once hesitated whether it was better to classify them according to genre or author. After counting the borrowing habits of many teachers and students, he found that the author's personality was more charismatic. Many students like one work and may come to the author with other works. So, he grouped everyone's work together and sorted the characters by chronology.

In this way, when you want to find a book, you have rules to follow. Even if you don't know the specific title, if you know what the general content is about, you can go directly to the corresponding area and search for it on the bookshelf.

Moreover, if you want to study a certain aspect in more depth, you can find many related materials on the same bookshelf at the same time, and you can compare them with each other without running around, so as to choose a more suitable book.

Located on the main campus of the University of Paris, this library is one of the most important of the bunkers. It is no exaggeration to say that it is currently the place with the most books in the whole of Paris, and indeed in the whole of France.

It is precisely because of such a large collection of books in the library that it has brought a lot of trouble to the classification and search of books. So, if you don't have a good index for your guests, it's almost like looking for a needle in a haystack to find a particular book.

Most people don't have the same good memory as Monsieur Pierre, and if you don't come here often, you may not know what kind of rules to follow.

The old-fashioned indexes were confusing, and simply trying to find the name of a book in them was as difficult as a lay person rummaging through the Bible for a particular word.

Even after so much hard work and re-arranging the bibliography, it is not easy for the reader to quickly become familiar with and master the method of searching.

Now that the library had been reorganized, he simply planned to adopt a new approach to indexing.

"So, you made such a thing?" Elena asked curiously.

In front of the service desk at the entrance, there is a small wooden cabinet that looks like a wardrobe. The doors are not like a wardrobe, but are equipped with all kinds of strange buttons, and the overall appearance looks like neat rows of lattices. The color of the cabinet is a more traditional black brown, and there is no special pattern, but each button is engraved with a different symbol.

"Let me explain." "The sixteen buttons on it represent different subject areas, including philosophy, religion, literature, history...... For example, this button with the sign of the cross is a number of religious texts and writings related to the Bible."

"Can this really help us find books?" Elena was a little skeptical.

"Don't underestimate him!" "It will help you find any book you are looking for," said Mister Pierre meaningfully.

"Huh? Really?"

"Of course, if it's included in this library." Mr. Pierre added, "It is not possible to create something out of nothing for the time being."

"Can you try that?" Elena asked.

"Of course." Pierre replied confidently, "What books are you looking for?"

"Hmm...... Let me think about it." Elena thought for a moment, "Are there any books about roses?"

"Is it botanical research on roses, or is it literature about roses?" Pierre further confirmed.

"I want to know how to cultivate it so that the rose in my room grows better." Elena replied.

"Okay, wait a minute." Monsieur Pierre said, and began to operate the device on the top of the cabinet.

I saw him press the second button in the third row. With a "click", the door of the cabinet automatically opened to both sides. This double-door design caught the eyes of several spectators.

Immediately after, a new button panel pops up inside. Identified above are some new symbols, acronyms for some words, to be exact, that are supposed to represent different fields of study. Monsieur Pierre chose one of the buttons with the floral motif and pressed it again.

With a "gurgling" sound, a second panel retracted, and then another panel rose up from the bottom. This time the buttons above are all words.

When the third button was pressed, the machine sounded a "ding-" sound.

At that moment, on the ceiling of the hall, three newly installed lights lit up and began to rotate at the same time. The light swept over the bookshelves and aisles, stopping at one point.

As a result, all three searchlights shone on the same bookshelf.

"Let's go and see."

So saying, Monsieur Pierre led them to the place where the lights were shining, and the shelves in front of them were filled with books on botanical studies and floriculture. Not only roses, but also roses, lilies, chrysanthemums, and so on.

"The trees are next door." Monsieur Pierre said, pointing to the shelf next to him.

On top are sycamores, pines and cypresses, and purple shirts...... A range of related bibliographies.

"How?" Pierre took down a copy of the Rosaceae Illustrated Book and showed it to Elena.

"Tsk, that's amazing." Elena exclaimed, "Amazing, Monsieur Pierre."

Regardless of the function, this sonorous style of mechanical operation is really handsome!

"Although it is only a trial stage, it can at least be used to a certain extent, so that everyone can find books." Mr. Pierre said.

The four of them returned to the front desk.

Monsieur Pierre pressed a button at the top of the cabinet, and with the sound of gearing, all previous operations were restored. I was back to the original panel.

"I said Pierre, have you applied for a patent for this thing?" Professor Pascal asked.

"Well, not yet." Mr. Pierre replied, "Because there are still many flaws, which are not perfect at the moment, they need to be improved."

"Huh? Any questions?" Elena asked, puzzled, "Is it that the daytime is relatively bright and the lights are not obvious enough?"

I've already used three lights, so even though it's daytime, I can see the location clearly.

"It's really the light, but it's not the intensity of the light." Pierre explains, "I was the only one in the demonstration, so there was no problem. But if you think about it, if there are many people looking for books at the same time, but there is only one machine, wouldn't it be more troublesome?"

If one person's book hasn't been found and the next person starts using it, the lights on it will move with it.

"Wouldn't it be nice to pack a few more?" Elena said disapprerovingly.

"It's not that simple!" Mr. Pierre shook his head, "The burden of electricity aside, even the space occupation is a tricky problem. The front desk is so big, and it can't be too many chandeliers on the ceiling, right? Moreover, if there are a few more sets of lights, it means that there is not only one light to indicate the location, in other words, it is easy to be distracted by other guides while looking for books."

With several directions, guests may be confused and wonder which one to go.

"Can you tell the difference between different colors of light?" Elena advised, "Just remember what color of light your destination is, and you won't get confused, right?"

"This can be differentiated, but it also brings other problems." "First of all, not all colors of light are suitable for reading. Some light can make the reader feel uncomfortable when they reach the shelf. Because from a distance, it is not possible to control the machine at any time and anywhere. And it doesn't have the function of its own, when a guest walks under the light, it will automatically turn off."

"It seems that Mr. Pierre has been more thoughtful." Bella said, "Have you ever thought that you could chart the location of a book?"

"You mean, a bibliography with charts?" "Isn't that the same as a traditional index? It's still a bit of a hassle to find."

"No, I mean, you can put your creativity into a traditional chart index."

"Uh...... An index that is integrated into the charts?" Monsieur Pierre still doesn't seem to understand.

"Well, how do you say that......" Bella paused for a moment, organized her language a little, and then described, "Your novel invention can help guests quickly locate books, right?" However, the direction of the location is achieved by means of lights."

"That's right."

"Well, we can keep this convenient way of searching. But you don't have to use lights to indicate the location, do you?"

"What do you mean......"

"Just give the final search results in the form of charts or numbers, just like a traditional index. And in terms of the way you find it, wouldn't it be the best of both worlds to use your creative approach?"

"That's right!" "This reduces the footprint of space and allows multiple people to use it at the same time without interfering with each other." Also, if it is only used for searching, the power consumption should be much saved."

There is no need for large-scale mechanical operation, only a small range of parts can be driven.

Mr. Pierre rekindled his fighting spirit and decided to develop a new retrieval machine.