''L'heptade'' is composed of seven core songs, in order: Comme un fou (Like a mad man), Chanson noire (Black song), Le premier ciel (The first heaven), L'exil (The exile), Le corridor (The hallway), Lumières de vie (Lights of life), and Comme un sage (Like a wise man). These seven songs were mainly written by band founders
Serge Fiori and Michel Normandeau. The title,
heptade, is the compound of two Greek affixes, hept- (seven) and -ade, which expresses both the notion of group (
décade,
pléiade) and epic movement (as in
Iliad). Fiori mentioned, at the beginning of the live album of ''L'heptade'', that the album, framed in seven songs, was evoking the journey of a man in one day through seven levels of consciousness; a rapid sigh of a man waking up, followed by steps on a cracked wooden floor can be heard in the prologue, the first musical movement preceding the first core song. A man preparing to sleep can be heard in the finale of the album. Each of the seven core songs includes from two to six different melodies, often with lengthy solos. Serge Locat performs on synthesizers, especially at the end of "Le premier ciel", and on piano in "Lumières de vie". The voice of Serge Fiori's
falsetto (head voice), sometimes broken by emotion, creates an emotional intimacy. His singing is often counterbalanced by a chorus formed by well-known Quebec singers of the time, including
Beau Dommage's Pierre Bertrand,
Les Séguin's
Richard, and
Ville Émard Blues Band's Estelle Ste-Croix. The signature of Harmonium, that is, the rich sound of the 12-string guitar, still remains the backbone of a few songs, particularly in "Comme un fou" and at the end of "Le corridor". But ''L'heptade'' offers a more sophisticated music than in the past. Lush arrangements, creative use of piano, electric piano, and synthesizers, and the sophistication of the melodies are some elements that set this album as full-fledged progressive rock. The other musical titles listed on the album represent musical interludes of classical, minimalist signature. These interludes are the result of the collaboration between Fiori and classical music composer and teacher
Neil Chotem, and are played either by a single synthesizer or with the
Montreal Symphony Orchestra. The lyrics of the album are mainly based around the personal, inner conflict of the main character. A major theme, recurring in all songs of the album, is the antithesis of the world: the Black and White, the Light and Darkness, the Day and Night. The struggle to unite these antitheses, which the lyrics in the first disc of the double-album, suggest is the source of the character's internal conflict, leads to the realization in the second disc that these antitheses can be overcome through love, but that true appreciation of love appears to be possible only with an uplifting mind. In the original cover of the album, the only printed lyrics were a section of "Lumières de vie", where the character begs to be spoken of love in order to overcome both nights and days (''...Lumières de vie... parle-moi d'amour, assez pour éclipser les deux [la nuit, le jour] pour toujours'').
Michel Normandeau, the co-founder of Harmonium, left the band at the beginning of the recording of ''L'heptade''. He thus appears only as contributing to the guitar playing of the first song, but he contributed to writing five of the seven songs. ==Production and performance==