How does Zuo Si's epic poems express his desire to make contributions?

This poem skillfully uses metaphor at the beginning, then introduces social reality with natural phenomena, and finally explains it with historical facts, so that historical facts are closely combined with reality and chanted, which is an important symbol of Zuo Si's maturity in chanting epic poems.

This poem says that "there is no poverty in the top grade and no family in the bottom grade" since the Wei and Jin Dynasties, "Jun Gao is the best in the world." The sharp contrast reflects the contradiction between the poor and the gentry, exposes the decay and darkness of the gate system, and cites historical facts to explain that it is an ancient thing for talents to create oppression. Such poems not only comment on reality, but also on history; What is condemned is no longer an accidental phenomenon, but a chronic disease of society; It not only expresses the author's personal resentment, but also represents the grievances of the poor throughout the ages.