zeppelin is definitely one of the better rock bands that were introduced during the late 60's, early 70's. however many bands fail to produce the same quality of tunes, so my question is basically what makes their tunes different? i don't really want this to be about the tones, the equipment or the era, which contributed to their overall sound and success - i want this to focus on the way the songs were written. for one, i have zero knowledge when it comes to theory, which leaves me guessing to why it is that they used the mixolydian mode for a lot of their songs, and how they even used that scale to produce the riffs they did. can anyone shed some light on this for me?