The album consists of a set played by Coltrane's quartet (augmented as a sextet with second saxophonist Pharoah Sanders and second bassist Donald Garrett) at The Penthouse on September 30, 1965.

At the end of the two-week gig, both Sanders and Garrett were asked to join the band, and accompanied it to the next engagement, September 27 - October 2, at The Penthouse in Seattle.

[4] During the stay in Seattle, Coltrane decided to document the newly-expanded group at his own expense, hiring the recording engineer Jan Kurtis for the September 30 gig.

[9] ("Afro Blue" features an alto saxophone solo by an unidentified player; it has been speculated that this may have been Carlos Ward or Joe Brazil.

Many other instrumentalists, seeking new ways to express their musical ideas, have gathered around Coltrane to absorb his ideas—which, in essence, have freedom as their goal...

"[14] The Allmusic review by Scott Yanow comments: "Coltrane experts know that 1965 was the year that his music became quite atonal and, with the addition of Sanders, often very violent.

This is innovative and difficult music that makes today's young lions (not to mention the pop saxophonists) sound very old-fashioned in comparison".

By Seattle, Coltrane had dispensed of conventional melodies in his own search for what Blind Willie Johnson had been looking for in the gospel blues: the soul of a man.

So the octane that Coltrane provided was pure turbulence, a streaming of notes too primal to contain, what you might call a speaking in tongues from a spiritual hermitage."

This is the final death - throes of the classic quartet and the lines are clearly drawn, Coltrane and Sanders on one side (with an assist from Donald Garrett) and Tyner and Jones on the other.