Have you ever fooled around with a radio by turning the volume dial up and down, up and down? That’s what hearing this poem is like. You’ve got the same basic "song" playing underneath: 10-line stanzas with iambic pentameter lines that rhyme. But it’s the speaker’s mood that really controls the dial.
The first four lines start off with a steady, even pace. The proper, old-fashioned language, including two "Thou"s, makes us think that a stodgy British professor type in a tweed jacket could be the perfect reader here. The voice is very modest and knowledgeable. At least until the poem starts talking about the content of the urn. In the next six lines, the dial is steadily turned. He’s like, "Oh, hello, what’s this? It looks like a ‘leaf-fringed legend.’ How interesting. Oh, my, are those "men or gods"? Maidens loth! Mad pursuit! Struggle to escape! Pipes and Timbrels! Wild Ecstasy!" Our dear professor’s glasses are getting foggy, and he’s racing through this list of increasingly exciting topics. As the volume goes up, so does the speed of the reading.
Ditto with the second stanza. It starts of with an authoritative, know-it-all tone, but after the first four lines it moves to address the guy playing pipes under a tree, and the speaker starts getting revved up. The big clue is when he repeats words, like the "never, never" in line 17. The third stanza has the volume way up, with the speaker close to hysteria. The repeated words make us pause to take short breaths in the middle of the lines, so that by the end of the stanza, we’re close to "panting" along with the men and maidens (line 27). In stanza four he turns the volume way down again, and the verse ambles along quietly just like the crowd of people walking behind the heifer. Things slow down to a crawl at the word "desolate," with its long first syllable. We’re talking about a silent little town, and the poem is almost hushed to silence.
Boom! The final stanza opens with two symbol crashes – that is, two exclamations in a row – as the dial suddenly goes all the way to the top. He gives us two more exclamations in the first five lines. In the final five lines, the poem returns to the tone of an even-tempered professor, mimicking the calm authority of the urn, who is a reassuring presence and a "friend to man" (line 48). We might expect this poem to end with the volume up again, but instead, it ends with the quiet mystery of the final two lines. Both lines are punctuated with big pauses – called "caesuras’ – in the middle. After the speaker’s mood swings throughout the poem, the air is charged with energy, but hushed.