They don't care about their appearance, but care about other more important things. It shows Mr. Wen Yiduo's simplicity and shows Mr. Wen Yiduo's diligence, seriousness and persistence in the revolutionary cause. Highlight Mr. Wen Yiduo's contribution to saving the country from the side.
He is delving into ancient books and records ... and he has been filming for a long time.
The light in the middle of the night is his companion, because he opens the way to light and is a "bleached wall". It shows Mr. Wen Yiduo's concern for the future of the motherland and the fate of the people. The ease of late-night research is in the same strain as "opening up a bright road."