Science, religion, and philosophy all rely on poetry and would be nothing without it. Religion, Arnold asserts, fails because it places emphasis on supposed facts, facts which do not always hold true. Conversely, poetry places greatest importance on ideas, and ideas will always hold fast. Without poetry, science would be meaningless. Science needs poetry to reveal the mysteries of nature and to illustrate life. Arnold's view of poetry places great pressure on it to be of the highest calibre: “if we conceive thus highly of the destines of poetry, we must also set our standard for poetry high, since poetry, to be capable of fulfilling such high destines, must be poetry of high order of excellence” (236). For Arnold, the distinction between truth and falsity, excellence and inferiority is more important in poetry than in prose because of poetry's higher purpose. The best poetry will have “power of forming, sustaining, and delighting us” like nothing else can (237).
Arnold identifies two major fallacies people make when judging poetry. The first is that they judge according to the history of a poet or poem. People give too much credit to a poem on the grounds that it is ancient. The second fallacy is judgement based on personal emotions. We tend to judge our contemporaries too harshly because of popular