Ye Wenjie walked toward the old faculty dormitory of Peking University, carrying a heavy grocery basket.
"Buying so many groceries?"
David, who had just gotten off the bus, happened to catch this scene. He stepped forward and proactively took the basket from her hand.
"There are many guests coming today, so I'm preparing a bit extra."
Ye Wenjie smiled kindly. Before she could finish her sentence, several primary school children ran out from the hallway and surrounded her.
"Oh... Nannan, you drew this? It's beautiful. You want me to give it a title? Alright, Grandma will help you write it as soon as we get upstairs."
"Yangyang wants to eat braised eggplant? Grandma bought many fresh eggplants today. You'll definitely eat your fill..."
Upon hearing Ye Wenjie's promise, smiles instantly broke out on the children's faces. Soon, holding hands, they ran off to play in the community's green space.
Ye Wenjie stood at the entrance of the hallway, squinting her eyes as she watched them with a smile. It was clear she was very fond of children.
"Professor Ye, which floor is your home on?" David asked, pulling his stray thoughts together.
"Fifth floor, East unit. The door with birch leaves pasted on both sides is mine," Ye Wenjie replied. She reached into her pocket, pulled out a ring of keys, and handed them to David.
"The longest one is for the security door. The key for the inner rooms is golden."
"I see. Is Yang Dong not home?" David asked with some confusion.
Since last night, Yang Dong had been urging him to leave early today. She had kept it up until now, making David feel a twinge of guilt for being ten minutes late for their appointment.
"Her? She probably has some sudden research task again," Ye Wenjie smiled and replied.
"That's how it is in their line of work. New discoveries can pop up anytime, anywhere... There might be a breakthrough, or there might not. But no one wants to miss the chance of success. For workers who truly want to leave something behind, inspiration is often fleeting."
David walked ahead, and Ye Wenjie followed him upstairs.
The hallway looked quite aged; most of the paint on the handrails had peeled off, and some steps had visible cracks. However, both the hallway and the residential compound were kept very clean, and a unique fragrance drifted through the air.
David nodded, turned the key, and opened the door.
The apartment was a standard family unit from the 70s or 80s, with high support pillars that carried a sense of distant history. The three-bedroom, two-living-room layout was conventional, but what truly surprised David was how well-preserved the rooms were.
Compared to the hallway, the interior was neat and organized. Aside from a few occasional smudges the size of a child's palm, the walls had no obvious damage. For an old house nearly thirty years old, this was quite remarkable.
"Xiao Su! I'll soak the vegetables first. There are far too many pesticides on vegetables nowadays. They need to be soaked for at least two hours before giving them to children."
David set the grocery basket down in the kitchen, and Ye Wenjie rushed over in a hurry.
"I'll prepare today's ingredients! Go rest in Ah Dong's (Yang Dong) room for a bit."
"That might not be appropriate," David felt a bit awkward. "I'll just sit on the living room sofa for a while."
"Nonsense."
Ye Wenjie's voice mixed with the sound of running water from the kitchen.
"There are photos of Yang Dong when she was a child in there. Don't look at her now; she was quite cute as a kid... Besides, she hasn't lived in this room for a long time since she went to college..."
David said he wouldn't, but his body honestly opened Yang Dong's bedroom door.
A scent of the forest greeted him. Birch leaves hung on the wall, and a row of small, crooked characters was written on an exquisite amber specimen:
"May the motherland's physics research cause forever prosper."
The room had very little furniture: just a bed, a desk, and a chair. True to David's first impression, Yang Dong's room looked like a ranger's cabin in the middle of a forest. The stump-shaped desk and the bed frame wrapped in bark patterns exuded an elegant atmosphere that felt detached from the mundane world.
David walked to Yang Dong's desk and looked at a photo of her in primary school, showing a brilliant smile he had never seen before. He shook his head, unable to connect the seemingly mischievous and cheerful girl in the photo with the cold physicist of today.
In front of the photo lay a diary with a birch-wood cover. David lightly brushed his fingers over the texture of the cover—dry, ancient, carrying the breath of history.
"Yang Dong's Birch-Bark Notebook."
At the very bottom of the cover, Yang Dong had written a line of small characters in a wobbly hand. He hesitated for a moment but ultimately did not flip open her diary.
"There are drawings Yang Dong made in kindergarten in the drawer."
Ye Wenjie appeared at the door at some point. She pointed to the drawer of the stump-shaped desk. David took out the carefully folded drawings.
"Those were her works from a drawing class organized by her school when she was in the senior class."
As David spread the colored lines across the desk one by one, Ye Wenjie leaned against the doorframe. Looking at the twisted world depicted by those naive brushes, she sank into deep memories.
"The drawings... well... they aren't very good..." Ye Wenjie hesitated before answering.
David nodded. Normally, a five- or six-year-old child should theoretically be able to depict the basic outlines and shapes of people. However, Yang Dong's drawings were filled with chaotic lines. David could faintly sense a feeling of powerless despair within them, like the melancholy of an infant trying desperately to express something but unable to speak due to their own limitations.
"In fact, many times I regret letting her encounter the world of physics too early."
The regret in Ye Wenjie's voice was genuine. "She is too smart, but also too sensitive and stubborn, just like my father."
David knew who she was referring to. Thinking of how Yang Dong had resolutely chosen suicide in the end, he fell into silence.
David opened the photo album on the desk. From left to right, as the photos progressed, Little Yang Dong's eyes grew more ethereal, and her expression became increasingly indifferent. By the middle school stage, David felt as if he were seeing a miniature version of the Yang Dong he knew.
"She came back in the third grade and told me for the first time that she thought 'those formulas are so beautiful.' I had a faint premonition back then."
Ye Wenjie looked at the old photographs in David's hand, her expression turned bitter.
"For a woman, this really is far too difficult a path."