Early Pink Floyd recordings make space travel superfluous so long as we have keyboards here on Earth. Back when enigmatic lyricist and acid-eater extraordinaire Syd Barrett skippered the ship, the Floyd sounded something like Monty Python with instruments -- quirky, trippy and weird. Barrett made Bedlam seem a reasonable price to pay for such gems as "Bike," "Lucifer Sam," and the Space Rock tour-de-force "Astronomy Domine." Upon Barrett's departure, the only marginally less maniacal Roger Waters took on singing and songwriting duties. The band dug even deeper into labyrinthine song structures, but nothing prior had prepared the world for 1973s Dark Side of the Moon. The concept album par excellence, Moon utilizes a narrative lyric structure and musical leitmotifs to give the album a sense of coherence. These compositional strategies culminated in '79s harrowing magnum opus, The Wall, an unflinching look at England's soul -- its educational system, its flirtations with fascism, the conservatism leading up to Thatcher. After Waters' defection, the remaining members came down with a crippling case of the blands but decided to stick it out, releasing a series of flashy (note '95's Pulse), nostalgic commodities that basically sounded like David Gilmour solo efforts (even if they continued to sell like genuine Pink Floyd productions).