Theoria - an album by Barry Guy and the London Jazz Composers' Orchestra, with pianist Irène Schweizer as soloist - documents a large-scale, 58-minute composition by Guy. The work is basically a concerto for Schweizer, and was presented in honor of her 50th birthday. As with many of Guy's compositions, the work attempts to find solutions to the challenges surrounding the coexistence of improvisation and composition. The score allows the musicians a considerable amount of freedom within a fixed structure. Schweizer recalled: "I had to read at times, but actually my part was free, I had a lot of room for improvisation."
In a review for AllMusic, Thom Jurek wrote: "This may be Guy's masterpiece in that here he has reached, finally, the perfect balance of incorporating all of his obsessions into one work: classical music, particularly the Romantic period, free jazz, new music, big band swing, blues, and soundtrack scores... Guy's entire sonic world opens up in color, tone, shade, and nuanced beauty. It is beyond language to interpret its effect, but its organization is so complex, so righteously taut with ideas and combinations of harmonic and contrapuntal interconnectedness it just boggles the mind even when looking at the score."
The authors of The Penguin Guide to Jazz Recordings wrote: "Guy attempts not to juxtapose blandly different styles of playing, but to overlap them creatively, creating diffraction patterns and points of maximum energy. In an orchestra of soloists, Schweizer stands out clearly but does not dominate; what happens is that her improvisations become the constituent elements of other musicians' activity."
Milo Fine wrote in Cadence-magazine, USA: „Two aspects of Theoria are particularly striking. The recurring syncopated orchestral riff is an unusual signpost for Guy, and therein lies its attraction. Of greater interest and import are the quick solo/small group change-ups with orchestral support during the last section of the piece. One hears not only a succession of individual voices, but a shifting textural tapestry as well. Put another way, these divergent concise statements blend to form a striking multi-timbred voice which is, in essence, the London Jazz Composers Orchestra."
Milo Fine, CADENCE, USA, April 1993
