The sigh and warning that "every grain is hard" is not an empty and abstract sermon, but a profound implication of flesh and blood. It reflects not the personal experience, but the life and destiny of the whole peasant. The poet chose typical details of life and well-known facts, and profoundly exposed the unreasonable social system.
"There are no idle fields in the four seas" means that all the land in the country has been reclaimed, and no field is idle. There is a fruitful and golden harvest scene everywhere. The working people have worked hard to create such great wealth. Is it reasonable to have plenty of food and clothing in a bumper harvest year? Who knows that sentence is "that farmer still starved to death." This is really shocking! The word "Jude" is thought-provoking: who deprived farmers of the fruits of their labor and trapped them to death? The word "I still starved to death" profoundly exposed social injustice and condensed the poet's strong indignation and sincere sympathy.