Li Bai, Du Fu and Bai Juyi are three poets with different styles of poetry creation. What is the reason of the times?

1. Li Bai was in the heyday of the Tang Dynasty and the country was strong. Scholars are eager to make contributions, and his poems show great ambition.

2. Du Fu was in the transitional stage from the prosperous Tang Dynasty to the middle Tang Dynasty, and experienced frequent class contradictions and wars. His poems naturally show a trend of worrying about the country and the people.

Bai Juyi lived in the middle Tang Dynasty, and the prosperous Tang Dynasty never came back, showing a declining trend. The poet felt that it was necessary to extend his brush strokes to the people in order to seek a good way to govern the country and save the country, so he advocated the "New Yuefu Movement".