Yixiong quickly stood next to Xinxiu. He also checked the surface of the table. The two of them then checked the other sides. It turned out that there were Hexagram carvings on each side of the table. Yixiong then ran towards the door on the east side. He shone on the door with his flashlight. On that occasion, he did so meticulously. Xinxiu followed Yixiong and stood to his right.

"Ah!" Yixiong shouted.

Xinxiu pointed his flashlight at the part of the door that Yixiong noticed. Yixiong was observing the top of the door. The door leaf was relatively high, which was about three meters. At the top, there was an engraving as well. It was clear that the shape of the engraving was a combination of the eight basic shapes of the Hexagram. The Hexagram has eight basic shapes. Simple was the right word to describe these basic forms. The hexagram combination combined the two basic shapes for a total of sixty-four shapes. The shape on the surface of the door leaf in front of them was six rows, each row comprising a long horizontal line.

The two of them then ran to the west wall. They found a six-line engraving in the same position on the door leaf, each line comprising two short horizontal lines. The shape was the opposite of the shape on the door on the east wall.

They cheered like children who had just received a new toy. They then sat on the benches there. Xinxiu guessed the symbols must have something to do with the way the doors were opened.

"Now, what should we do? Go to the surface to tell our friends?" Yixiong said as he tapped his fingers on the surface of the stone table.

"Not now," said Xinxiu. "Our findings don't change things. We still don't know how to open these doors. So let's hold off for a moment. Let's think about it here."

The two of them then sat pensively on the cold stone benches.

"Xiongge, the carving on the door is a combination of two basic shapes. But the basic shape used is the same. The carving on the door on the east is a combination of two basic hexagram shapes in the form of three long horizontal lines, while the carving on the door on the west is a combination of two basic shapes in the form of three pairs of short horizontal lines."

"Xiudi, maybe the meaning of the symbol is the emphasis on the basic shape of the Hexagram. So, we should only focus on the shape of three long horizontal lines for the east door, and six short horizontal lines, or what you call three pairs of short horizontal lines, for the west door."

Uh? That is a good idea!

They then checked the side of the stone table in front of them once more. At that time, they checked much more thoroughly than before. Every inch of the table did not go unnoticed by them. Not only the table's surface, but they also check the legs and the bottom of the table. But so far, they have found nothing.

Xinxiu sat back down on the cold bench. He twirled his flashlight so that its light flashed across the walls of the room.

"Stop it. The flashlight is so dazzling!" Yixiong shouted.

Xinxiu laughed. He stopped his action. "There must be something we've missed."

Yixiong asked, "when are we going back to the surface?"

Xinxiu didn't answer. He got up and walked back to the door on the east side. Then he turned and approached the door on the west side.

"The Hexagram engraved on the top of the door is a combination of the two basic shapes. There are eight basic shapes. The combination of the two basic shapes results in sixty-four Hexagram shapes."

Yixiong just stared at Xinxiu. Xinxiu felt Yixiong was only listening to the words he had just spoken. It was clear that Yixiong had no idea whatsoever. Maybe later, after breakfast, he could think more clearly, so Xinxiu could ask him to discuss. But that's not a guarantee. Most likely, Yixiong still didn't know what to say.

"According to Xiongge, why were those Hexagram combination were used, not others Hexagram combination?" Even though he knew Yixiong could not answer, Xinxiu kept asking.

Yixiong just shook his head. Xinxiu knew that there was no point in forcing Yixiong to think under such circumstances. Unexpectedly Xinxiu, suddenly a brilliant idea slid out of Yixiong's mouth.

"On the top of the east door are engraved six lines, each of which is a long horizontal line. It is a combination of the same two basic shapes. The basic form is three long horizontal lines. The west door is the same, the carving is six rows each. Each row comprised two short horizontal lines. The basic form is three lines, each line comprised two short horizontal lines. Why are the two the same shape chosen? Why not different shapes? Maybe the solution lies there!"

Could that be the key to this puzzle?

"The Hexagram shape on the east door symbolizes 'Force,' while on the east door it symbolizes 'Field.' Does this have something to do with how we can open the doors, or is it about the contents of the rooms or passages behind the doors?" Xinxiu spoke those words out loud. Of course, he asked himself. He didn't expect Yixiong to answer the question.

"What if the two identical shapes stacked together don't represent a combination of Hexagrams? But it illustrates that there are two things being talked about?" Yixiong said.

Xinxiu listened to Yixiong's words as he again shone the flashlight at the door and the ceiling. Then he gasped. "The base shape on the east door symbolizes 'heaven' while the base shape on the west door symbolizes 'earth.' If the two basic forms of heaven are combined, it symbolizes 'force', while the combination of the basic forms of 'earth' symbolizes 'field.' So, according to Xiongge, it is possible that the shape of the carving on the east door does not symbolize 'force' but symbolizes two 'heavens'. While the shape of the carving on the west door also does not symbolize the 'field,' but two' earths.'"

"But what are the two 'heavens' and the two 'earths'?" Yixiong muttered.

Xinxiu ran towards the stone table. Yixiong followed him.

"The 'heaven' and 'earth' engravings are on this table. Maybe in this room there are other places that contain 'heaven' and 'earth' carvings as well," said Xinxiu.

"We can't possibly drag all the cupboards on the four walls of this room to check every inch of the wall behind it. That is definitely a time-consuming and labor-intensive thing," said Yixiong.

Xiongge is right. Our time is minimal. But, at least we have to try!

Xinxiu groped the part of the wall that had not previously been covered by the wardrobe-like objects, namely the corner they had come from earlier. The wall was made of concrete, which looked very solid. So it's not made of stone like the octagonal table in the middle of the room. Xinxiu muttered, "Which part of this room is made of stone, just like that table?"

Suddenly, Xinxiu jolted like an electric shock. He rushed back to the table. There, he immediately kneeled and examined the bench in front of the side of the table. The benches were also made of stone. Carefully, Xinxiu examined every inch of the bench. The bench was rectangular. At the bottom of the side of the bench facing the table, Xinxiu found the basic shape of the Hexagram engraved there.

Yixiong also checked the other benches. In the same position, he also saw the carving of the basic Hexagram shape. They both cheered again, like when they had just found the Hexagram engraving on the top of the two doors. But it's not over yet. They had found the two 'heavens' and the two 'earths' in question but did not know what the connection between the two of them was with how to open a locked door.

Finally, Xinxiu said, "I think it's time we tell them about our discovery. Maybe after knowing this, they'll have a better idea."