Somewhere up in the sky Syd Barrett shines on – or at least does the part of his brain he used to sing with.

Pink Floyd, the band Barrett helped to make famous with his insanity, offers Echoes, a greatest hits album, combining popular favorites with Barrett’s early work.

Barrett’s work often inspires one thought: “This is lunacy.”

“Bike,” which Barrett wrote for his girlfriend, has the memorable line, “I’ve got a mouse and he hasn’t got a house / I don’t know why I call him Gerald / He’s getting rather old but he’s a good mouse.”

Lunacy perhaps, but there is no denying the brilliance of Floyd’s music. All the strange relationships, paranoia, social commentary and weird instruments are on Echoes.

Echoes samples the band’s most famous songs, including “Wish You Were Here” and “Shine on You Crazy Diamond” (which the band wrote after losing Barrett). The result is a truly complete Pink Floyd experience.

Floyd purists may object to the displacement of these songs from their concept album order. The concern is not entirely unfounded. These tracks do lose their original context but, somewhat surprisingly, the tensile strength of the common thread running through Pink Floyd’s body of work is enough to hold Echoes together as a successful albumin its own right. Even though Floyd never conceived these songs to be heard together, they are seamlessly engineered to flow coherently for an hour of continuous music on each of two CDs.

For those who still think Pink Floyd is the name of the lead singer, Echoes is an opportunity to discover that they’ve got a bike, a very nice bike. You can ride it if you like.