This is Mr. Guo Moruo's evaluation of Du Fu. The last sentence comments on people, and the next sentence discusses poetry. The last sentence "worry" refers not only to Du Fu's vicissitudes of life, but also to the war Du Fu experienced-An Shi Rebellion. "Sage in Poetry" is generally recognized as the title of "Sage in Poetry". The next sentence "people's sufferings" means that Du Fu's poems extensively involve and reflect people's sufferings. "Wave at the bottom of the pen" not only means that Du Fu's pen is magnificent, but also his poems are of great artistic value. It also reflects Du Fu's emotional tendency, that is, he cares about people's livelihood, shares the sorrow with the people, and the people mourn, so his feelings are turbulent.
The first case: An Shi Rebellion
The second situation: worrying about the country and the people.