Shine On Brightly was influential in the development of progressive rock by breaking pop and rock music standards with the 17-minute epic "In Held Twas in I", which marked the beginning of the lengthy progressive rock suites that would occur later in the 1970s.
The title of the epic "In Held 'Twas in I" is an acrostic, taking the word from the first movement as well as the first word from a verse later in the movement as well as taking the first word from each of the three successive movements as shown:
Shine On Brightly was released in September 1968 by record labels Regal Zonophone and A&M. The original British and North American versions of the opening two tracks ("Quite Rightly So" and "Shine On Brightly") are different versions.
The album was reissued several times, including a 2009 remaster using the original 2-track stereo masters and featuring bonus B-sides and alternate takes. However, many of the tracks are played at a higher speed.
Upon its release, Jim Miller, writing for Rolling Stone, was unfavourable: "Procol Harum's first release was generally more satisfying, especially since this new album displays little in the way of startling growth – the group has apparently chosen to refine their old approach and the musical result, while usually listenable, is not consistently interesting."