Dusk has barely settled, and Edward Thomas has already stripped the world down to a few things: two birds, a moon, the ground. In "Two Pewits" nothing happens except that the birds fly, yet the poem is full of a question. The pewits "sport and cry" over "the ghost who wonders why / So merrily they cry and fly." The poem sets their careless movement against that puzzled watcher below, and it never settles the matter.
The opening picture is built from extremes. The birds are "More white than is the moon on high" and "More black than earth." That suits a bird with black-and-white plumage against a darkening sky, but it also does something larger. The pewits seem to carry the two poles of the landscape in their own bodies, light and dark, sky and soil. This helps explain why they "Nor choose 'twixt earth and sky." They don't need to choose, because they already belong to both. The slightly old-fashioned "'twixt" gives the line a fairy-tale lilt, as if the evening were being told rather than described.
The most striking thing about the poem's construction is its rhyme. All fifteen lines end on the same long "i" sound: sky, cry, high, why, fly. "Silently," which closes lines 4, 14 and 15, is a softer, unstressed echo of it. The poem doesn't even bother to vary its rhyme words. "Sky" ends four lines and "cry" ends three, so the poem circles back to the same few words again and again. Since "pewit" is a name that imitates the bird's call, the effect is hard to miss. The rhyme becomes the bird's cry, one note repeated, and the poem seems to be calling in the same voice as its subject. It also traps us under the sky, since the word keeps arriving at the end of the line like a horizon we can't pass.
The rhythm is loose and playful. Lines swell and shrink, from the full stretch of "Under the after-sunset sky" to the tiny, tripping "And merrily they cry." Short lines feel like quick turns in flight. In "Plunging earthward, tossing high," the two present participles do the work of a dive and a lift, and "earthward" and "high" sit at opposite ends of the line so we feel the drop and the climb. "Now low, now high" balances in the same way, like a bird tilting from one wing to the other.
Sound matters as much as movement. The cry is "the one sound under the sky," and the line break after "Their cry" lets the word hang in the air before the sentence continues. Around that single sound the poem builds silence. The moon is "Riding the dark surge silently," a phrase that turns the night sky into a dark sea. At the end the moon "Rides" again and "earth rests as silently." Quiet frames the cry on both sides. The poem does claim that the birds "alone move," even though the moon is also riding, but the moon is so slow and soundless that it barely counts. The birds seem to be the only living things in the scene.
Then there is the ghost. The poem gives no explanation of who this is, and any answer is an inference from the text. The ghost lies beneath the birds ("Over the ghost"), so it is earthbound, and it is the only one who asks questions. It might be a human watcher made thin and spectral by the strangeness of the hour, or someone who cannot join in the fun. Next to the "mischievous Spring sky," which seems to be in on the joke, the ghost looks solemn and left out. The birds don't wonder why they are merry. They simply are.
That is where the poem's quiet significance lies. It makes no argument and draws no moral. It gives us a scene made from plain words and one repeated sound, and it leaves us in the ghost's position, looking up and wondering why such gladness needs no reason.