Rather than restrict himself to Peruvian literature, Vargas Llosa also looked abroad for literary inspiration. Two French figures, existentialist Jean-Paul Sartre and novelist Gustave Flaubert, influenced both his technique and style. Sartre's influence is most prevalent in Vargas Llosa's extensive use of conversation. The epigraph of "The Time of the Hero", his first novel, is also taken directly from Sartre's work. Flaubert's artistic independence—his novels' disregard of reality and morals—has always been admired by Vargas Llosa, who wrote a book-length study of Flaubert's aesthetics, "The Perpetual Orgy". In his analysis of Flaubert, Vargas Llosa questions the revolutionary power of literature in a political setting; this is in contrast to his earlier view that "literature is an act of rebellion", thus marking a transition in Vargas Llosa's aesthetic beliefs. Other critics such as Sabine Köllmann argue that his belief in the transforming power of literature is one of the great continuities that characterize his fictional and non-fictional work, and link his early statement that 'Literature is Fire' with his Nobel Prize Speech 'In Praise of Reading and Writing'.