With every vastly different phase of their evolution, Pink Floyd broke new ground and evoked different perspectives on previously untraveled sonic galaxies. Their 1967 debut The Piper at the Gates of Dawn was a psychedelic masterwork, as was most of the celestial and eccentric rock the band created with their early leader, Syd Barrett. After Barrett's premature departure in 1968, the group spent five years wandering through experiments before bassist Roger Waters emerged as chief songwriter, developing a deep fascination with mundane matters of ego, mind, memory, and heart, to...