Day thirteen of proving the Song He Manifold.
Lunch was stewed mutton in the Northwest style, with tender meat simmered in clear golden broth. A large bowl sat brimming before him.
Song He was acting completely out of character. Usually, he would have wolfed down the food by now, but today, with a big bowl of mutton in front of him, he remained motionless, staring quietly at the scratch paper on the table, like a chess player studying the board.
Scratch paper was piled thickly across the table, covered in densely packed, tiny handwriting. His eyes were vacant, and he did not move at all.
Xiang Xiaotong sat at the desk beside him, tapping away at her computer as she worked. After a long while, she happened to turn her head and glance over. She let out a surprised sound.
"Why aren't you eating?" Xiang Xiaotong walked over and patted him on the shoulder.
"Eating?" Song He froze for a moment, then looked down at the bowl in front of him. "Oh, the food's here!"
"You've been out of it these past few days." Xiang Xiaotong frowned.
"It's frustrating. I've run into a problem with proving the Song He Manifold that's hard to solve. I've tried more than forty approaches, and every single one ended in a dead end." Song He sighed repeatedly. "I've used every trick I have and tried every bit of knowledge I've learned. None of it worked!"
"You've tried all the knowledge you've learned?" Xiang Xiaotong pondered for a moment. "What about knowledge you haven't learned?"
"I don't even know which direction to study in!" Song He pulled a bitter face.
"No, no, I phrased that wrong. I mean, your known tools aren't working. Have you ever thought about creating your own tools?" Xiang Xiaotong asked.