Exhibit E:
Their BBC sessions from 1969 and 1971 Especially "Dazed And Confused", when it gets all Ash Ra Tempel-like and whispery for just a coupla moments
http://digilander.libero.it/vinylcollector/ledzep.h4.jpg
I think their best LP cover, it outpeppered the Beatles in it's quasi-mystikal ghosts of WW1 psychedelic way. If the band knew what it all meant I'll be disappointed :-)