First, I must say I'm not a big follower of prog, so I doubt I'll be able to contribute much to this thread. I'll leave that to the experts. I just thought this might be a topic that might generate interesting viewpoints as to the birth of prog. Anyway, I've been reading Tyler's book, and here's a quote from him: "The Yardbirds were so strange and unpredictable. They could make a pop song like 'For Your Love'(with its minor key) sound dirge-like and ominous. We're talking f**ked up time-traveling R&B monks. Gregorian chants! Outlandish Australian wobble-board percussion! Harpsicords and bongos! The Yardbirds used minor thirds and fourths like alchemists. They were really the first progressive rock band, with their use of Eastern melodies on 'Over Under Sideways Down' the howling sirens on 'Happenings Ten Years Time Ago'. I loved their weirdness and their mystery."