All the joys can be obtained from labor, and all the hardships can be understood from labor liberation as labor is the source of happiness. According to the relevant public information, this question mainly examines the students' understanding and analysis ability. The stem part emphasizes that pleasure comes from labor and hardship is relieved by labor, which means that labor is the source of happiness, all pleasure can come from labor, and all hardship can be relieved by labor. This is Li Dazhao's famous saying.