On one of their next stops Sokka complained that they had far too less information about the Firenation, after the girls and Aang had decided to each choose a spot for vacation. Sokka was not happy with their plans for vacation at all, for he thought there was no time as it was. But Aang wanted to have some time off. Katara picked the "Misty Palms Oasis". Aang claimed it to be one of nature's wonders, a natural ice-spring in the middle of the desert. Unluckily it turned out that the ice-spring had melted a bit and was now only a small bit of ice steaming in the hot desert-air.
There was a tavern there, but it seemed run down, as did the whole place, and the people really didn't look as if they were to trust. They watched the barkeeper using his doubleswords to create some fruity drink for one customer, and so Sokka wanted to have one too. Unluckily Aang ran into the said customer, spilling his drink all over Aang's clothes. He dried himself up with Airbending, before Zuko could stop him. The guy got excited at once, calling Aang a living relict and introduced himself as Professor Zei. He was overly excited about meeting an airbender and started taking notes about Aang immediately.
Sokka used the encounter to ask for a newer map, since theirs seemed to be a bit outdated. Unluckily the map of the guy was only of the area, and not of the whole world as Sokka had hoped. The professor told them he was looking for Wan Shi Tong's Library, but had not managed to find it yet. This library was built by the knowledge-spirit himself, according to the legends, by collecting wisdom from all over the world for mankind to read in order to better themselves. As Sokka found out it might contain a map of the firenation or any other useful information about it, he chose his vacation was the library. The professor though put in that it was not so easy to find, and that the desert was almost impossible to cross, for he had tried several times and nearly died each time he had tried. So Sokka decided to introduce the guy to Appa.
It took really some time to find the library. And for the air wasn't really cooling up there, crossing the dessert over and over again was not really much fun. Sokka even used his shirt to make a hat to protect his head. Toph made fun of them by calling out "There it is." Causing all of them to react. Finally Sokka spotted a tiny tower sticking out of all the sand. As they landed next to it, they figured out that it had to be the very top of the library and that the rest had to be buried down in the sand. They were sure, once a fox-like creature appeared with a scroll in its muzzle, running up the tower with ease and disappearing through a window at its top.
Toph told them that despite the building was nearly completely buried, it still seemed intact and that it was enormous. She read that from touching the tower's walls. Sokka decided they had to climb up and through the window as well, like the knowledge-seeker-fox they had seen before, but Toph decided she would stay outside. So they left Toph with Appa outside, since she was not really into books, and climbed up the tower with the help of a rope tied to Sokka's boomerang used as a grappling hook. They used the same technique to go back down on the other side as well. The tower seemed to be clad with gold, ending in a massive stone-dome. They finally landed on some stone-bridges guarded by columns at the edges that showed a massive owl on top of each column.
They hurried to hide as they heard someone coming closer though. The someone was a gigantic looking owl with black feathers and a white face and two white spots on the back of its head. "I know you are back there." It said, causing the Professor to step out of their hiding. He hurried towards the owl, introducing himself. "You should leave the way you came." The owl said. Aang decided they should come forward as well, and doing so he asked the owl if he was the spirit who created the library. The owl then introduced himself as Wan Shi Tang and told them that humans were no longer welcome in the library, since one Firebender came to look for information to destroy his enemy. And since humans only used wisdom against each other, Wan Shi Tang did not allow them in his studies any longer.
"So, who are you trying to destroy?" he asked, looking at Sokka. "What? No, nono, no destroying." Sokka hastened to say "We're not into that." "Then why have you come here?" the spirit asked. "Uhm… Knowledge for knowledges sake?" Sokka suggested. The spirit called him lies, but Sokka pushed Aang forward, telling the spirit he was with the Avatar. Aang promised that they would not abuse the knowledge of the library, so the spirit decided he would allow them to use his collection under one condition. They had to contribute some knowledge. The professor gave up a book and the spirit agreed with it and took it. Katara offered her Waterbending-scroll she stole from the pirates so many days ago. Aang took out a wanted-scroll of himself and Sokka made a dragonfly-puppet out of a piece of string. All Zuko could think of having was the knife they had found with him. It had an inscription at least, maybe it would count. The spirit took their offers and let them go explore the library.
They went to explore therefor. Sokka continued to simply put things in his bag. Then he found some paper underneath some glass, and he took it out too, hurrying away. The others followed, asking him where he was heading. "I want to know what happened to Firenation on their darkest day." Sokka explained. They found a room with a red banner on top with the symbol for fire printed on it in a black letter. Unluckily the room was completely empty and burnt. Sokka was devastated about this. Luckily a fox-being came along, whining until they decided to follow it. It lead them to a gigantic golden plate, seeming to symbolize the sun. As the fox slipped through a hole in the wall, the inner plate started to move and showed a room behind it. There was the fox again, and a round altar-like thing in the middle of the round room.
The fox pushed a lever and suddenly a layer started to cover the dome-ceiling showing a night-sky as well as the solar system. The Professor called it a planetarium.
Katara suggested to try to enter the digits from the piece of paper Sokka had found on the altar, which turned out to be some sort of calendar-thing. So Sokka started to turn the disks which made the top layer of the altar to the date that the piece of paper was claiming to be the darkest day in Firenation history. Then he pushed the lever again, and the planetarium started moving. It stopped suddenly, leaving the room dark, despite it was having the day-layer out. As they looked up they saw that the moon-symbol was covering the sun-symbol. "Great. It must be broken…" Aang huffed. "It's not broken. The sun is behind the moon." Sokka explained "It's a solar-eclipse. It's literally the darkest day in Firenation history. Something horrible must have happened on this day. I do not know what but I do know why. Firebenders lose their bending during a solar eclipse!"
"That makes sense." Katara said "Think of what the lunar eclipse on the North-pole did to the waterbenders…" Sokka gave a treat to the fox and it headed off. "We have to get this information to the earthking in Ba Sing Se." He then decided. "Shush!" Zuko warned "Remember what we promised. We can make plans once we are out of here…" The others nodded. But first they decided to look when the next solar eclipse was going to be. And they actually found out that one was going to be before Sozin's comet arrived. Sokka noted it down. "Now we better get going and do not push our luck any further." Zuko decided. "Are you insane? I won't leave this building ever again!" the Professor cried out. "Well, then don't. But we better get going." Zuko decided "Come now." Katara, Aang and Sokka nodded and hastened for the door.
They didn't find any maps on their way, but they came just in time to find Toph fighting against some sand-benders trying to steal Appa. "Hey!" Zuko yelled at them, attacking at once. Katara and Aang joined in and so did Sokka. They had the sandbenders running in no time. "Was about time." Toph grumbled. "We hurried…" Zuko sighed "Now off to Ba Sing Se." They all climbed onto Appa and started their way towards the earthkingdom of Ba Sing Se. Thanks to a map Sokka had liberated from the library they could use the stars to guide them towards Ba Sing Se.