William Wordsworth was one of the Romantic poets. Accordingly, many of his poems were written as celebrations of the beauty and of the healing power of the natural world. Romantic poets also wrote nostalgically about the innocence of childhood. All of these themes are evident in Wordsworth's "To A Butterfly."
In the first stanza of the poem, the speaker implores a butterfly not to fly too far away from him. The opening line, "Stay near me—do not take thy flight!" is phrased as an imperative sentence, meaning that it begins with a verb and is phrased as an order. It is also an exclamatory sentence, as are five of the lines in this opening stanza. Thus, the tone is demanding and forceful rather than gentle or playful, and this implies that the speaker is somewhat desperate for the butterfly to stay close.
In the third line of the first stanza, the speaker says that he finds "Much converse" in the butterfly. To "converse" with someone or something means to talk and communicate with them, so the speaker is suggesting here that the butterfly speaks to him—not literally, of course, but in a figurative sense. The following line, "Historian of my infancy!", offers some clarity. The butterfly "converses" with the speaker in the sense that it reminds him of or speaks to him of his past and, more specifically, of his childhood or "infancy." The speaker says that "Dead times revive" in the butterfly, meaning that the butterfly reminds the speaker, or seems to bring back to life for him, memories of his childhood. At the end of the stanza, the speaker suggests that these memories are "solemn." We find out in the second stanza that the memories themselves are not "solemn" but rather the fact that they are gone, or "Dead," is "solemn."
The second stanza begins with the speaker seemingly fully immersed in the memories of his childhood. The exclamation "Oh!" as the opening word suggests that the speaker is perhaps a little overwhelmed with how "pleasant, pleasant were the days." The specific memory from his childhood that the butterfly evokes is a memory of his sister, Emmeline, and himself chasing a butterfly. The energy and vitality of childhood is evoked when he describes how they chased the butterfly "with leaps and springs . . . from brake to bush." The poem concludes with an image connoting the delicacy and beauty of the butterfly, as the speaker remembers that his sister was anxious not to hurt the butterfly or "brush / The dust from off its wings." It seems appropriate that the poem should conclude with an image connoting the butterfly's beauty and delicacy, because the butterfly is itself a symbol of the beauty and delicacy of the speaker's childhood memories. These memories are beautiful because they are full of energy and, like the butterfly, color. They are delicate because, now that he is an adult, those memories are perhaps faded and more difficult to grasp.
Most of the poem is written in iambic tetrameter, meaning that there are eight syllables to most lines and that the syllables in those lines follow a pattern of alternating stresses. For example, in the line "A little longer stay in sight!", there are four iambs, or pairs of syllables, and in each, the second syllable is stressed. This creates a kind of lilting rhythm. The final syllable in each of these lines is always stressed, which creates a rising meter. In other words, because the final syllable is stressed, one reads the lines with a rising intonation. Altogether, the iambic tetrameter creates an upbeat, lilting rhythm, which echoes the positively soothing nature of the speaker's memories of his childhood.
Occasionally there are lines which break the pattern of iambic tetrameter, such as "Dead times revive in thee" and "My father's family." These lines are still iambic, but they consist of just three iambs, meaning that they are iambic trimeter rather than iambic tetrameter. When occasional lines break a pattern as these lines do, they stand out as slightly rhythmically dissonant. The fact that these two lines appear at the end of the first stanza perhaps reflects the slight feeling of solemnity that intrudes upon and interrupts the otherwise happy and sentimental mood of the speaker. His mood is disrupted by a slightly darker mood at this point in the poem, as he remembers how these memories are "Dead" and never to be revived. This disruption to his mood is reflected in the rhythm of the poem also being slightly interrupted at the same point.