The title track "Octavarium" is the longest track on the album, at 24:00, and divided with five parts. Petrucci stated that the band wanted to write an epic song that thematically developed and would use an orchestra. The band was heavily influenced by the progressive rock sound of Genesis, Yes and Pink Floyd. The instrumental introduction, heavily influenced by Pink Floyd's "Shine On You Crazy Diamond", was performed by Rudess using a lap steel guitar and Continuum. Additionally, there are many references to other progressive rock songs in the lyrics. The song ended with the first note of "The Root of All Evil" before fades-out (instead there's an alternative version for some releases, with the reprise flute from the first part of "Octavarium" playing in the background). Both of these sections indicates that they weren't continue the last note for chain to their next album, despite the band never explicitly stated the both sections.