Octavarium (song)

"Octavarium" is the eighth and final track on Dream Theater's 2005 album of the same name. It is an epic, progressive rock composition lasting over 24 minutes. The song is notable for its structure, which loosely follows a musical octave, with each of its five main sections (apart from the instrumental introduction and outro) being influenced by a different musical style, reflecting the albums previous tracks and their corresponding keys.

The song begins with an instrumental section, "Someone Like Him," which sets the stage for the thematic journey to come. This section transitions into "Medicate (Awakening)," influenced by U2 and in the key of C. Following that is "Full Circle," reminiscent of Pink Floyd and in the key of D. The next section, "Intervals," draws inspiration from arena rock bands like Journey and is in the key of E. "Razor's Edge" reflects the style of bands such as Muse and is in the key of F. The song then builds to its climax with "Sacrificed Sons," a more complex and heavier section in the key of G. Finally, it returns to the opening motif, this time in the key of A, creating a complete musical octave.

The lyrics of "Octavarium" deal with themes of cyclical patterns, inevitability, and the search for meaning. The lyrical content of each section also reflects the musical style it embodies. The song serves as a capstone to both the album and the band's overall discography, thematically connecting to previous albums and songs.