Task: Question Answering
Input (English): Passage: Apart from a single early work for unaccompanied choir ("Chanson à boire", 1922), Poulenc began writing choral music in 1936. In that year he produced three works for choir: Sept chansons (settings of verses by Éluard and others), Petites voix (for children's voices), and his religious work Litanies à la Vierge Noire, for female or children's voices and organ. The Mass in G major (1937) for unaccompanied choir is described by Gouverné as having something of a baroque style, with "vitality and joyful clamour on which his faith is writ large". Poulenc's new-found religious theme continued with Quatre motets pour un temps de pénitence (1938–39), but among his most important choral works is the secular cantata Figure humaine (1943). Like the Mass, it is unaccompanied, and to succeed in performance it requires singers of the highest quality. Other a cappella works include the Quatre motets pour le temps de Noël (1952), which make severe demands on choirs' rhythmic precision and intonation.Poulenc's major works for choir and orchestra are the Stabat Mater (1950), the Gloria (1959–60), and Sept répons des ténèbres (Seven responsories for Tenebrae, 1961–62). All these works are based on liturgical texts, originally set to Gregorian chant. In the Gloria, Poulenc's faith expresses itself in an exuberant, joyful way, with intervals of prayerful calm and mystic feeling, and an ending of serene tranquillity. Poulenc wrote to Bernac in 1962, "I have finished Les Ténèbres. I think it is beautiful. With the Gloria and the Stabat Mater, I think I have three good religious works. May they spare me a few days in Purgatory, if I narrowly avoid going to hell." Sept répons des ténèbres, which Poulenc did not live to hear performed, uses a large orchestra, but in Nichols's view it displays a new concentration of thought. To the critic Ralph Thibodeau, the work may be considered as Poulenc's own requiem and is "the most avant-garde of his sacred compositions, the most emotionally demanding, and the most interesting musically, comparable only with his magnum opus sacrum, the opera, Dialogues des Carmélites.". 
Question: What is the title of the work that is "the most avant-garde of [Poulenc's] sacred compositions," according to Ralph Thibodeau?
Output (English): Sept répons des ténèbres.