To dissect one of my favorite songs of all time seems disrespectful.

It's a cool one! Drums are cool, singing cool, guitars maybe some of the coolest Jimmy Page devised. John Paul Jones has a pretty basic job on bass but also layers in an essential organ part into the verses.

Formally, this song has no sung choruses. There are fantastically fun, harmonically brilliant verses, while the song's defining guitar melody serves as the refrain. It's a Page and Plant duality par excellence. And the song has only these two parts, progressively gaining intensity, until there is a great instrumental development played just before the big ending. Formal novelties like this are the rule on the entire album on which this song appears - the incomparable Houses of the Holy, maybe the best rock record ever made.

Just a unique combination of melody, modality, rhythm, and instrument sound. Led Zeppelin at their most sonically visionary.