Coleridge begins by doubting himself. "It may indeed be fantasy," he admits, when he tries to draw "deep, heartfelt, inward joy" from created things and to read in leaves and flowers "lessons of love and earnest piety." The verb "essay" means to attempt, and it is a modest word. He is trying something, not claiming a discovery. Then comes the shrug that drives the whole poem: "So let it be." If the world laughs, its mockery brings "nor fear, nor grief, nor vain perplexity." The central idea is that a private faith found in nature needs no public approval, and that a field can serve as a place of worship as fully as any built church.
The sonnet's structure carries this argument. The first eight lines rhyme ABBA CDDC, and they are defensive: first a concession, then a refusal to be shaken. At line nine the poem turns from defending to building: "So will I build my altar in the fields." That "So" echoes the one in line six. The earlier shrug has become a decision. The sestet rhymes EFEF and closes on a couplet, and its mood is calmer. The octave argues, and the sestet pictures.
The rhythm is mostly a steady iambic pentameter, which suits the speaker's composure. Line seven, though, breaks the pattern: "In mock of this belief, it brings" has eight syllables where its neighbours have ten. The effect is that the world's mockery gets clipped short and dismissed before it can take up much room. The next line then lists what the mockery cannot cause, "Nor fear, nor grief, nor vain perplexity," and the list grows to end on a four-syllable word, which the "nor" has already denied. The list swells and then deflates.
The sestet is built on a single extended image, nature as cathedral. The speaker's altar stands in the fields. The sky becomes a "fretted dome," and "fretted" suggests the carved, interlaced decoration of a vaulted ceiling. The scent of a "wild flower" becomes incense. The word "wild" matters here, because nothing in this church is cultivated, bought or built by anyone else. The speaker also plays on the word "yields." The flower "yields" its fragrance, and he in turn will "yield" it to God. The repetition makes a small chain of giving, from the flower to the speaker to heaven.
The title is "To Nature," yet the poem's last address is to "Thee only God!" The word "only" reads like a deliberate boundary. Nature supplies the building, the ceiling and the perfume, but it is not the one being worshipped. That is an inference from the text, but the grammar supports it: the "Thee" and "thou" at the end are capitalised and directed upward, past the flowers.
The final couplet also shifts the poem's anxiety. At the start the speaker feared being mocked by the world. By the end he hopes only that God "shalt not despise / Even me, the priest of this poor sacrifice." "Despise" answers "mock," but the stakes have changed, and now only one judge matters. The humility is striking. He calls himself a priest, yet his offering is "poor," and the phrase "Even me" admits that he feels unworthy of the role. The confident builder of an altar turns out to be a nervous worshipper.
Coleridge is remembered as a Romantic poet, and many readers first meet him through the strange, supernatural worlds of "The Rime of the Ancient Mariner" and "Kubla Khan." This sonnet is quieter and plainer, closer to a prayer overheard. It shares the Romantic habit of finding meaning in the natural world, but it joins that habit to a clearly religious devotion. What makes it worth reading is its honesty. The speaker does not pretend to be certain. He grants that he may be deluding himself, then chooses to go on believing and worshipping anyway. Within fourteen lines, the sonnet's form lets him move from doubt to resolve to a humble hope.