Right. The rock and roll modes of playing are fairly constricted. They stay within the same chord tones, chord progressions, modes when used… I'm not really against intellectual property but as a music nerd and theory student, self-taught, I think that it's really hard to 'own' anything except for what you yourself play/record..especially if you are commercially selling it. IT's not like Zeppelin word for word copied the lyrics or even kept the arrangement quite near the same. So at the end you have this:
Major 6th - Root (Tonic), Major 7th, Dominant 7th, 6th then 6th, 5th, flat5th, 4th, 3rd
E G Gb F E E D Db C B
Thats the bass line and main riff- it is pretty novel sounding to me but that's how it breaks down. Corect me if I'm wrong but I hear it as in the key of G major. G major key consists of..
G A B C D E F# (G)
1 2 3 4 5 6 maj7 octave. (octave isn't in the scale but I put it there to emphasize where you go after the major 7th…. and that'd make the B7 they drone on and riff around the 3rd… .. so it's a chromatic walkdown in G major starting oddly on the 6th, shooting up to the root… then walking down skipping only one note chromatically to the major 3rd (B7) … so what's cool about the bass line. .that first ba dum…( E G ) is that it tricks the mind/ears by going from a very low note that is a fairly uncommon way to introduce the key of the song… right an octave up to the root .. ba DUM dum.. dumm… dum that one i put in caps being the G is the root note…. so the song gives this eerie feeling that you're falling away from where you should be by taking the listeners ears constantly descending , almost teasing you, away from the root! droning on practically every note and riffing on a B , the major third!! this is even more torture. because why the hell am I hearing the major 3rd's dominant 7 chord being emphasized when we haven't EVEN ESTABLISHED THE FUCKING ROOT!?!? Donald trump is going to complete German idealism. This terrifies me. I'm not sure what they were thinking when they composed this. Please sign my petition.