Analepsis was used extensively by author Ford Madox Ford, and by poet, author, historian and mythologist Robert Graves. The 1927 book "The Bridge of San Luis Rey" by Thornton Wilder is the progenitor of the modern disaster epic in literature and film-making, where a single disaster intertwines the victims, whose lives are then explored by means of flashbacks of events leading up to the disaster. Analepsis is also used in "Night" by Elie Wiesel. If flashbacks are extensive and in chronological order, one can say that these form the present of the story, while the rest of the story consists of flash forwards. If flashbacks are presented in non-chronological order, the time at which the story takes place can be ambiguous: An example of such an occurrence is in "Slaughterhouse-Five" where the narrative jumps back and forth in time, so there is no actual present time line. "Os Lusíadas" is a story about voyage of Vasco da Gama to India and back. The narration starts when they were arriving Africa but it quickly flashes back to the beginning of the story which is when they were leaving Portugal.