I’m gonna get all classic rock on y’all again. Expanding on Bobby Owsinski’s analysis of Led Zeppelin’s iconic “Stairway To Heaven” from November, I decided to geek out about the theory behind the tune in a little more detail. I realize it’s a rock song and not a film score, but there are some interesting and educational things to learn from the unusual way it’s crafted. In this post I’m also borrowing from and adapting Spy Tunes excellent piece, “How ‘Stairway To Heaven’ Used Modal Scales to Reach the Top.”
Despite “Stairway’s” eight-minute length, it’s relatively simple under the hood. Most of the melody uses just six notes (and their octave equivalents), and there are only five basic chords in the song. Structurally it has four main sections, two of which are related, and one is nothing more than a brief interlude. The apparent intricacy of the tune comes from its use of slash chords, modal interchange, the melodic, harmonic and rhythmic development throughout the song, and of course the remarkable musicianship of the band.
The basic chords in the song are A minor, C, G, D and F Major 7. Pretty simple for an eight-minute tune. In reality, the harmony is a little more complicated than that though. Some of the chords appear as slash chords, or chords with a different bass note. G frequently appears with a B in the bass (also known as G in first inversion, or G/B). D similarly appears with an F# in the bass (D first inversion). The song also contains C/G, C/D, and Em/D. But most of these chords are fairly common, even in guitar writing.
The one truly unusual chord in the song is a bit of a doozy though: A minor add 9 with a G# in the bass (or Am(add9)/G#). It’s the second chord in the song, and because of that prominent placement, it contributes a great deal to the track’s unique sound. Played on its own it’s a fairly dissonant chord—we tend to hear the chord as a variation of A minor, but with the unusual addition of a G# in the bass, making it a rather crunchy A minor/major 7. It’s also got a tense major seventh interval between the C and the high B. In context, though, the chord makes perfect sense: the A bass from the opening chord drops a half-step to G#, and the high A raises a whole step to B. Thus, in the fabric of the song the voices flow smoothly and we hear the notes in terms of horizontal motion rather than vertical dissonance and the chord doesn’t sound discordant.
It’s also interesting to note the differences between the opening verse and verses 2–5. Melodically, the verse are identical, but harmonically they’re quite different. Aside from ending on an Amin chord, the chords have been completely rearranged and now revolve around C instead of Amin. Yet because of the melodic consistency, most listeners probably never notice.
From this point on the harmony is straightforward. Aside from the aforementioned slash chords, the song is harmonically fairly simple and easy to follow. I’ve charted out the entire song so you can see all the chords in context.
As Spy Tunes points out, “Stairway” is essentially a modal tune. What’s interesting, though, is that the song doesn’t stay in one mode. It vacillates between two related but distinct modes: A Dorian and A Aeolian, and it makes stops in A melodic minor as well. Until the end vamp, the song never remains in any one of these modes for long, which keeps the song engaging and gives it an ethereal, ambiguous feeling.
The song opens in what seems to be A minor (or A Aeolean in modal terms). It begins on an A minor chord, which could be either A Aeolian or A Dorian. The second chord, though, is that weird Am(add9)/G#, which can only be A melodic minor (essentially a major scale with a minor 3rd). This isn’t even one of the standard modes, so immediately we’re in strange harmonic territory. The third chord, C/G, could be in either A Aeolian or A Dorian, but the fourth, D/F#, is clearly in A Dorian as there is no F# in A Aeolian. The fifth chord, Fmaj7, takes us back to A Aeolian for the same reason—no F natural in A Dorian. Finally, the last two chords, G/B and Am, could be in either mode. Thus there’s only one chord that is definitively in each of the three modes, but the ambiguity in between keeps our ears guessing.
Once we get to the “chorus” section—”It really makes me wonder…”—the modal ambivalence disappears and the song settles for a moment into A Dorian. The following verses, however, stick firmly to A Aeolean. So this section of the song continues the modal see-saw of the A section but on a larger scale—the verse is Aeolean and the chorus Dorian.
The instrumental interlude, at 5:34, is clearly in D Mixolydian—the same key, G major, as A Dorian. The ascending D-E-F-G melody and the drop to C make this plain. The following solo/outro section is in A Aeolean, due to the Amin-G-FMaj7 progression, ending the song on a note of modal clarity. The track, which began in extreme ambiguity, cartwheeling between modes on almost every measure, finally settles down into familiar territory and resolves to a familiar three-chord A minor progression.
As I mentioned earlier, the melody essentially consists of six notes: A, B, C, D E and G. Interestingly, these notes are all common to both A Aeolean and A Dorian. The melody skips the sixth scale degree entirely, which is the only difference between the two modes. This only reinforces the modal ambiguity of the tune—until the solo, the melody doesn’t take sides at all in that debate, and so the chords remain in limbo. It’s a marvelous bit of restraint, and a brilliant reminder that melodic simplicity is key, even in a song as long and as subtly complex as this.
It’s not until the solo that we get our first F, that elusive sixth scale degree. Since this section also prominently features an FMaj7 chord, we’re clearly in A Aeolean now, and it’s safe for Page to let go of the modal ambiguity. We’re also firmly in rock territory, and the song is now plowing it’s way to the finish line in awesome grandeur. All the ethereal dreaminess of the first few sections is gone, and we’re comfortably in a three-chord race to the end.
For the most part, the song is rhythmically fairly simple. There’s a consistent 8th-note pulse through the first 5-1/2 minutes, created first by the guitars and later the drums. The big rhythmic surprise in this section are the fills John Bonham does at the end of each vocal couplet. He anticipates the end of the second line by a full measure, adding a fill under the vocal instead of after it, where most drummers would. Not only does this defy expectations—always a good thing—but it really drives the song and emphasizes the syncopation at the end of each line.
By far the most unusual rhythmic touch in the song is the instrumental interlude at 5:34. The entire rest of the song is in straight 4/4, but suddenly the band is dropping and adding beats, and even half-beats, like nobody’s business. Most notably, after the second D(sus4) chord there’s an extra 8th note, making for a really odd time-warped feeling. Suddenly the beat isn’t where you thought it was, as if the band just teleported to 1971 from the quasi-medieval folk world of the first 5-1/2 minutes and caused a temporal glitch in the process.
There are likely a number of different, and equally good, ways to chart out the rhythm here. I saw one tab that turned the second 3/4 measure into 7/8 and placed the C chord on the upbeat at the end of that measure. But the more I listened, the more I felt the downbeat landed on the C chord, and the eighth note was added in between the first and second beats of that measure. It’s almost as though the band is taking a breath before the big finish. However you write it out, it’s much easier to feel the rhythm than to count it. Thanks to Bonham’s magnificent drumming, the odd time signatures seem to flow by almost unnoticed, a frequent feature of Zeppelin tunes. Bonham was a genius at simplifying and playing a straight beat while the rest of the band did God-knows-what (see “Black Dog” and “Kashmir“).
Putting It All Together
I realize this all sounds very technical, and you may well be asking why anyone should bother analyzing the song at this level of detail. Surely most listeners—99% of them, likely—don’t have this level of music theory knowledge and wouldn’t notice all of this anyway. True, but the point of analyzing a song like this is to find out why it works, and hopefully give you new ideas for your own compositions. Modes, chords and melodies work whether we understand them or not. The tonal quality of “Sympathy for the Devil’s” Mixolydian verse/major key chorus works whether you know what Mixolydian means or not. “Oye Como Va” is a catchy melody even if you never realize it’s in the Dorian mode. Likewise, the haunting, ambiguous nature of Stairway works its magic even if you never understand the theoretical reason for it. Indeed, Spy Tunes claims the band didn’t even know what they were up to, they just knew they had something good. Clearly, as “Stairway’s” prominence as one of rock’s greatest masterpieces will attest.