Similar examples are:
Zuo Zhuan Yin Gongyuan: Zhi, Ye, Shu Bi died. -Uncle Guo died there.
Thirty-two years of Zuo Zhuan's Nuogong: How can we keep the bones? -I collect your bones there.
The Analects of Confucius: the way of a scholar is three, I can do anything. -There's nothing I can do about these three people.
Zhuangzi's idea of keeping in good health: After listening to my words, I got a good health. This is the way to keep healthy.
Because of its position at the end of the sentence, it gradually has the nature of modal particles.
Example:
Mencius: I serve my country faithfully, which can be explained as: I serve my country faithfully. When "Yan" and ""appear at the same time, pronouns are diluted.
Even become pure modal particles.
Example:
The Analects of Confucius: Confucius said: a gentleman is ill and incompetent, but a patient doesn't know.
However, the standard usage of Yan should still be demonstrative pronouns and modal particles.