In his essay “Robert Frost”, Auden begins by discussing the tension or rivalry between Ariel and Prospero, which he believes denote two opposing tendencies or magnetic poles in poetry.

Although “every poem shows some sign of [both]”, and although “every poem involves some degree of collaboration between Ariel and Prospero”, nonetheless “the role of each varies in importance from one poem to another.” Hence, despite their being mixed together in different ratios in different works, “it is usually possible to say of a poem and, sometimes, of the whole output of a poet, that it is Ariel-dominated or Prospero-dominated.” What distinguishes these two?

Ariel is represented (critically, Auden notes) by Keats’ line, “Beauty is Truth, Truth Beauty!” This magical spirit stands for the priority of beauty over truth or the supposition of their simple identity. In Ariel-dominated poetry, we want to be taken away from the intractable problems of life, we want “a verbal earthly paradise, a timeless world of pure play.” This is the domain of the artificial, das Künstliche, in the strongest sense. Any consequence other than beautiful play is subordinate to it or ignored. Lack of utility, even lack of sense, is relished, and we take pleasure in being transported to realms of imagination that need not touch base anywhere, zones of fancy and flight.

But, Auden notes the crucial if obvious point: “Art arises out of our desire for both beauty and truth and our knowledge that they are not identical.” As much as we enjoy the remove of Ariel-dominated poetry, we also know we cannot be fooled forever by the paradise of play: we demand to hear about the truth.

Hence the tension with Prospero: He represents our desire for the poem to not exclude the evils we face, to tell us something true about life, to not merely provide a momentary oasis or escape. We want poetry also to be a revelation that will “free us from self-enchantment and deception.” This means that the poet must introduce into their poetry “the problematic, the painful, the disorderly, the ugly.” Quoting Samuel Johnson, the goal for the Prospero-type of writing is “to enable the readers better to enjoy life or better to endure it”—to endure it as it really is, not beautified or made-up.

Were he asked for an example of “good poetry”, Auden says he would likely pick an Ariel-type poem. In admiring it, one would talk about “language, the handling of the rhythm, the pattern of vowels and consonants, the placing of caesuras,” indeed all the elements that count toward greatness in writing qua writing.

But, if he himself were in a state of “emotional excitement, be it joy or grief,” he would seek a Prospero-type poem, a poem that is “relevant and illuminating to [his] condition”, in which the “beautiful verbal element [while not absent] is subordinate in importance to the truth of what it says.”

The distinction then, we could say, is between the aesthetic excellence of ‘pure poetry’ and the interpersonal excellence of ‘life wisdom’. Between linguistic refinement and human sympathy? Between perfected craft and existential honesty? Between the artistic veil and the nature it covers?

Auden, for his part, expresses his dissatisfaction with Ariel: he “has no passions. That is his glory and his limitation.” He creates a paradise, but nothing of “serious importance” can occur there. In the long run, such verse can “repel us by its narrowness and monotony of feeling: for Ariel’s other name is Narcissus.”

The advantage, however, for an “Ariel-dominated” poet is that he “can only fail in one way–his poem may be trivial,” ridiculous, a botched concoction of words, sounds, and images that simply aren’t beautiful, a failed experiment from which we may move on. If Ariel fails, we only say, “That poem need not have been written.”

Whereas Prospero, who is “trying to say something true”, can actually produce something false—existentially false. Thus he can fail in multiple ways, for here the error is to not see reality aright, to lead astray into falsehood and false life. If he fails, we will say, “That poem should not have been written,” and even, “The man can’t write.”