Pratt's "Butterfly Effect" begins in the middle of a gesture. "This one," the speaker says, as if holding a butterfly out on a fingertip, and then the sentence trails off without a verb, offering only two possible origins. The butterfly comes either "from the milkweed growing against / all odds on the edge of my driveway" or from among "those rescued from a predator / in Polly's patch." We never learn who Polly is. The phrase suggests a neighbour's garden, but the poem doesn't say, and it doesn't need to. What matters is the scale: a driveway edge, a small plot, one rescue. The poem happens in the margins of ordinary life.
Then comes a question: "Remember the story / that one might change the weather of the world?" This is the popular idea behind the title, that a butterfly's wings in one place might help set off a storm far away. The poem quietly corrects it. "Maybe not the movement of its wings. / Maybe just the vision." The change that counts isn't meteorological but human, and it happens in whoever is watching. The central idea is that small, fragile things alter the world by being seen, and that their influence travels through the people they move.
The form suits that modesty. There is no rhyme and no fixed metre, though most lines hover around ten syllables, enough of a steady pulse to feel composed without sounding like performed verse. The syntax carries more weight than the sound. The poem is built from fragments and a question. The opening has no verb, and neither does "Maybe not the movement of its wings." The final sentence stretches into a colon, a list and a question, and its last line runs slightly longer than the others. The effect is of someone thinking aloud and hedging. "Maybe" begins two consecutive sentences, so the poem proposes rather than declares.
Small repeated words do much of the work. "Against" appears twice, with different meanings. In the opening lines the milkweed grows "against / all odds," and the line break leaves the word hanging, as if the plant were leaning on something. Later the butterfly is "fragile against a leaf." In the first use the word means defiance, in the second a light touch. One preposition ties toughness to delicacy, so the plant and the insect seem to share the same stubborn survival. "One" does similar work in "This one," "one of those," "that one might change." It keeps the focus on single things: one plant, one rescued insect, one possible observer.
The imagery is brief and well chosen. The colours, "brave orange / and black," are split across a line break, much as a wing's pattern is divided into bands. The word "butterfly" never appears in the body of the poem, only in the title. Instead the speaker says "animal," a plain, slightly surprising word that gives the insect creaturely dignity. "Brave" is a bold adjective for something so slight, and the next line complicates it: the butterfly is "blown across the sky." The creature supposedly able to change the weather is at the weather's mercy. This suggests its bravery lies in carrying on regardless, which makes it a better emblem for the speaker's hope than the grand myth was.
The last two lines turn on "change," which has already appeared once, in the weather line. At first it belongs to the world, then to the butterfly in "what it's like to change / that way," where readers may hear the transformation from caterpillar, and finally to the human witness in "who knows who, seeing it, will change?" The word passes from the sky to the animal to the viewer, a small butterfly effect of its own. The tight echo of "who knows who" adds a note of wonder to the question. The poem ends on that question mark with no answer.
What makes the poem worth reading is its restraint. It takes a phrase worn smooth by repetition and gives it a human, believable meaning. It doesn't promise that one act will reshape the world. It says only that being moved by something small may be how change begins, and that nobody can know whom it will reach. The speaker's own actions, tending milkweed and rescuing a butterfly from a predator, quietly suggest that she has already been changed.