Across the history of pop music, there are certain years that feel more momentous than others. Moments in time where the social conversation, artistic trends, and brightest minds converge to create a hotspot of musical innovation that stands out among the arbitrary dividers of time.

One of those years is 1967, a year of psychedelic mastery that continues to unfold new masterpieces to me.

The few years before, the Beach Boys and the Beatles had upped the ante considerably. The Beach Boys released Pet Sounds, largely in response to the Beatles’ Rubber Soul. The Beatles fired back with Revolver in 1966 and Sgt. Pepper in 1967.

And after that, it was a massive free-for-all. It felt like every band was fighting tooth and nail to stretch pop music beyond itself—a challenge that led to Brian Wilson’s mental breakdown.

British rhythm&blues band Moody Blues may not have meant to start any sort of revolution when they went into the studio to record their second full-length, but they ended up doing just that. Days of Future Passed combined their Beat and R&B songwriting with a full orchestra. And quite on accident—with no money to pay for recordings, the group was asked by Decca Records to work with an orchestra to demonstrate the capabilities of their new recording equipment. The thought was to show how well the technology worked for classical and pop compositions alike.

But the Moodies had a different idea. They used the time to develop an adaptation of a stage musical they had been working on about the day of an ordinary man. Orchestral passages would link the songs together, creating a pop music suite. It worked far

It was unlike anything released before—and is now regarded one of the first progressive rock albums.

The record is remarkably cohesive, considering that the band and the orchestra rarely play together ( the climax of “Nights in White Satin” is the lone exception). Instead, the two groups of musicians feed off one another, passing themes and motifs back and forth between one another.

It’s a fantastic idea, and it’s masterfully executed. But it’s all the more impressive by how cohesive it is between the two groups. The orchestra often feels like the soundtrack to an old Disney film (in the best way possible), while the band shifts from dramatic r&b (“Dawn: Dawn is a Feeling“) to surfy psychedelic rock (“Lunch Break: Peak Hour“), and honky tonk (the early moments of “The Afternoon“). The band performances are marked by keyboardist Mike Pinder’s new Mellotron keyboard, a sound that become inescapable among psychedelic and progressive rock.

Not bad for what was intended to be a throwaway demonstration piece.