While the first five and a half minutes illustrate sophisticated organic growth, the solo is entirely comprised of repetitions of a new two-bar phrase (g). The rhythmically unstable Transition B followed by new material emphasizes the arrival of the solo as the climax of the song.
5:56-6:45 (D) Solo (20 measures)
(g) |a G |F | x10
The seventh and final verse adopts the same (g) two-bar phrasing of the solo, repeating it 13 more times (for a total of 26 measures) with Plant adding vocals to the first nine phrases.
6:45-7:47 (D') Verse 7 (26 measures)
6:45 (g) |a G |F | “As we wind...”
6:50 (g) |a G |F | “Our shadows...”
6:54 (g) |a G |F | “There walks...”
6:59 (g) |a G |F | “Who shines...”
7:04 (g) |a G |F | “How everything...”
7:08 (g) |a G |F | “And if you listen...”
7:13 (g) |a G |F | “The tune will come...”
7:18 (g) |a G |F | “When all are...”
7:22 (g) |a G |F | “To be a rock...”
7:27 (g) |a G |F | [instrumental]
7:32 (g) |a G |F | [instrumental]
7:37 (g) |a G |F | [instrumental]
7:42 (g) |a G |F | [instrumental]
The final four phrases are instrumental and ritard the tempo, leading to...
The coda wraps things up be reprising the title lyrics and melody used several times earlier in the song. This final iteration, however, omits any underlying chord changes, leaving Plant's vocals fully exposed.
7:47-8:02 Coda “And she's buying...”
Aaron Krerowicz, pop music scholar
An informal but highly analytic study of the music of Led Zeppelin.