In terms of tonal architecture, Charles-Marie Widor began his second set of organ symphonies, the four works of Op. 42, published in or around 1880, precisely where he left off with the previous set. The keynotes of the four organ symphonies of that first set (Op. 13) are C-D-E-F, and the Symphony No. 5 for organ, Op. 42, No. 1, is set in the same key as the last of those symphonies: F minor (and, significantly, the four works of Op. 42 outline a keynote scheme parallel to that of Op. 13: F-G-A-B). In the Symphony No. 5, which today may be the most frequently played of Widor's organ symphonies (and certainly contains his most famous movement), we can hear the composer beginning to explore, tentatively and just a little bit at a time, a more chromatically-involved musical palette than he allowed himself in Op. 13.
The Organ Symphony No. 5 is in five movements, making it the most compact -- in terms of movement-total, not duration or musical language -- organ symphony yet. Compared to the slim, quasi-improvisatory Toccata that opens the Symphony No. 4 in F minor, the opening Allegro vivo of the Symphony No. 5 is a massive, solidly built movement whose arch-shaped main idea is put through many changes of timbre and character, including a scherzando central episode, over the course of 15 pages of music. With the next movement, the somewhat unusual layout of the Symphony makes itself plain: two quick movements and then two slower movements and a finale. If the goal is to find a traditional symphonic layout in the work, the Allegro cantabile second movement can be considered a kind of scherzo, and the two slower movements, Andantino quasi allegretto and Adagio, might be thought of as a kind of conglomerate slow movement. The energetic Toccata that ends the Symphony, with its repeating, ever-modulating subject, is easily Widor's most famous piece. It is often performed by church organists as a stand-alone composition.