In 1977, "Suspiria" had been an unexpectedly big box office hit for 20th Century Fox, released in the U.S. under their "International Classics" banner. Capitalizing on the commercial success of the film, Argento and Daria Nicolodi, who had co-written the screenplay, announced that "Suspiria" was only the first of a proposed trilogy which they referred to as "The Three Mothers" trilogy. The basic concept of all three films is derived from Thomas de Quincey's "Suspiria de Profundis", a sequel to his "Confessions of an English Opium-Eater". A prose poem of the book entitled "Levana and Our Ladies of Sorrow", details how, just as there are three Fates and three Graces, there are also three Sorrows: "Mater Lachrymarum" (The Lady of Tears), "Mater Suspiriorum" (The Lady of Sighs) and "Mater Tenebrarum" (The Lady of Darkness). As the title suggests, "Suspiria" focused on Mater Suspiriorum; the evil sister featured in "Inferno" is Mater Tenebrarum. The concluding chapter of Argento's trilogy, "The Mother of Tears" (2007), is about Mater Lachrymarum.