The poem's first trick happens before the first line. "Cat kin" is the word "catkin" pulled apart, and a catkin is the soft, furry flower cluster that hangs from willow branches in early spring. The word itself comes from an old Dutch word for "kitten." Splitting it in two gives the title a second meaning: kin, as in family. The willow and the cat become relatives, and the poem's first image, "white fur on the willows," treats the tree as an animal with a pelt. The comparison is quiet and affectionate, and it makes spring seem less like a botanical event than a creature stirring.
What follows is a swerve. "Till it all burst into infinite novelty" is by far the longest line, and it behaves like what it describes. Where the first line is calm and visual, this one rushes forward without punctuation, and the stresses tumble through "infinite novelty" in a light, bouncing run. The poem never says what bursts. The fur, the willows, the whole season, or the world all seem possible, and "it all" lets them blur together. The verb "burst" also puts a small violence into the softness. Fur is gentle, but this opening-out is sudden and almost too big to contain.
Then the poem stops and asks a question, though without a question mark: "who knows the world for it." The line is made of short, plain words, and after the long line before it, it slows the poem right down. It can be read at least three ways. Who can know the world except through this bursting? Who knows the world better because of it? Or who knows the world for what it is, once it has become this novel? The missing punctuation lets all three stay alive. It also gives the line a hushed, wondering tone, as if the speaker is thinking aloud and not announcing a conclusion.
The final line grounds everything: "dressed in yesterday's dust." The grammar is loose here too, so we can't be sure what is dressed. It might be the willows, the world, or the "infinite novelty" itself. This is where the poem's central idea arrives. Newness never comes from nowhere. Each spring's "infinite novelty" puts on old clothes, with the same dust, the same tired ground, the same world as yesterday. The sound supports this. "Dressed," "yesterday's" and "dust" share a hard d, so the line has a dry, crumbly texture that contrasts with the soft "fur" and "willows." After the lift of "novelty," the poem comes down to earth in a single beat.
The structure is just as spare. There are four lines, each standing alone as its own stanza, with no rhyme, no capitals, and no punctuation. The white space between the lines acts as the pause between thoughts, and the reader must carry the connections across it. The lengths run from five words to nine, then six, then five, so the poem swells in the middle and shrinks back, like the burst it describes. Its form is close to the compressed, image-led style of haiku, although it makes no strict claim to that tradition. The plain vocabulary matters because it keeps the grand phrase "infinite novelty" from sounding inflated. It is the only abstract, big-sounding phrase in the poem, surrounded by fur, willows and dust.
The poem is worth reading closely because it holds two truths about renewal at once without choosing between them. Spring really is astonishing, and it really is a repeat. The poem suggests that wonder doesn't require the world to be clean or new, since the dust of yesterday is part of what the new thing is wearing. That makes the question in the middle line feel earned. If the world always arrives this way, glorious and dusty together, then perhaps we only know it by noticing both. In four short lines, the poem moves from a pun to a cosmos and back to the dust on a twig, and it does so without raising its voice.