This sentence comes from Bai Juyi, an advocate of the New Yuefu Movement.
He said in "Nine Books with the Same Yuan": "Since I came to North Korea, I have become older and more knowledgeable. Every time I talk to people, I ask more current events, every time I study history, I seek more truth, and I know that articles are written in the times and songs and poems are written in things. "
Bai Juyi's sentence means that writing articles should be close to reality, facts and the pulse of the times, which is also a writing principle that people today should follow.