Days of Future Passed is the second studio album by English progressive rock band the Moody Blues, released on 17 November 1967, by Deram Records.

These changes, combined with a shift away from R&B covers toward original compositions and a thematic concept, helped define the band's sound for the next several albums and earned the group new critical and commercial success.

Instead, the album features original compositions expressing the day in a life of an everyday person, interspersed with orchestral interludes arranged and conducted by Peter Knight and performed by the London Festival Orchestra.

The band would find guitarist and singer Justin Hayward through Eric Burdon of the Animals, who had put out an advert for a new bandmember of his own.

New singer and guitarist Justin Hayward explains, "We were originally a rhythm-and-blues band, wearing blue suits and singing about people and problems in the Deep South.

We were lower middle class English boys singing about life in the deep south of the USA and it wasn't honest.

Developed by the West Midlands company Streetly Electronics in the early 1960s, the instrument served as a precursor to sampling keyboards and synthesizers.

"[13] Pinder continues, "Les Bradley of Streetly electronics gave me a call and told me that he had found me a suitable instrument at the Dunlop tyre factory social club.

"[15] An October 1967 Sunday Mirror article gives the price of the band's Mellotron at £1,300, which was paid for by an air conditioning business millionaire, Derek McCormick.

"[13] Edge remembers, "Mike figured out to add horns, strings, bagpipes and all that sort of stuff behind it and turn it into a more natural musical instrument.

"[18] The instrument's ability to reproduce orchestral string sounds in the studio and in concert paired well with Ray Thomas' flute, which he had recently adopted in place of harmonica.

Its lyrics acknowledge the spirit of the ongoing Summer of Love and embrace the feeling that society was approaching a new sense of enlightmentment, a new spirituality.

I knew by then, by the time I had written "Tuesday Afternoon," that we were going to do this stage show that was based on a day in the life of one guy, even before we recorded the album.

"[18] Lodge explains the theme of "(Evening) Time to Get Away": "It's really about, if you can achieve something every day, it doesn't matter how small it is, it just gives you that energy to carry on and have an enjoyable life.

Hearing the final BBC mix of "Nights in White Satin" heightened the band's excitement for the song and their new material.

Band members remember being asked by the label to record an album incorporating elements of Antonín Dvořák's Symphony No.

Thomas explains, "They wanted a demonstration disc made for all the salesmen to try and sell Deramic Sound and we could never get any studio time.

"[34] Eager to capitalize on the opportunity for studio time, and confident in the quality of their newly written material, the band agreed to the label's plan and then quietly decided to record their live set of original songs instead.

[31] Recording sessions for the album took place at Decca Studios in West Hampstead, London beginning with "Dawn Is a Feeling" on 18 October and concluding on the 27th, with mixing complete by 3 November.

"[11] The band worked with record producer Tony Clarke, engineer Derek Varnals, and conductor Peter Knight.

If you look at other things we did at the time that weren't in the Decca studios, they're much more rock 'n' roll and piano based and trying to be a little more up-front and thinking of singles.

"[11] The orchestral interludes were recorded during a single session on 3 November,[31] and were performed by the London Festival Orchestra conducted by Peter Knight.

[32] Hayward remembers, "When we played the finished product to all these old directors at Decca, which is a fine, upstanding old English music firm, they said, 'This isn't Dvorak,' and we said, 'No, but this is what it is.'

"[18] The cover features a painted collage of various time-related images inspired by the album's songs, including an hourglass, a sunset, moon phases and mounted knights.

[43] In the US, it was a steady seller in the late 1960s, helped by FM radio play of "Nights in White Satin", and eventually peaked at number 2 on the US Billboard chart in 1972.

On 17 November 2017 this original mix was made available for the first time on CD as Days of Future Passed 50th Anniversary Deluxe Edition.

[46] Upon its release, Rolling Stone gave the album an unenthusiastic review, writing "The Moody Blues [...] have matured considerably since 'Go Now', but their music is constantly marred by one of the most startlingly saccharine conceptions of 'beauty' and 'mysticism' that any rock group has ever affected.

[50] By 2007, Rolling Stone — which had originally described Days of Future Passed as "an English rock group strangling itself in conceptual goo"[53] — included it in its list of the essential albums of 1967.

But there is a sharp pop discretion to the writing and a trippy romanticism in the mirroring effect of the strings and Mike Pinder's Mellotron.

"[8] Will Hermes cites the album as an essential progressive rock record and opines that its use of the Mellotron, a tape replay keyboard, made it a "signature" element of the genre.