Resnais commented on his plan in an interview: "Films or plays usually arise from a desire to develop an idea or theory through characters or through a story. I said to myself, 'Wouldn't it be fun to do just the opposite? To allow theory and fiction to coexist on the screen.'" The screenwriter Jean Gruault developed the fictional strands, after reading all of Laborit's works himself, and in continual discussions with Resnais. This led to a screenplay in which three fictional characters would take Laborit's theories as their starting point but their interwoven stories would then develop in their own way. The process of writing the screenplay took one year. Resnais also added the idea of using black-and-white extracts from old films to explore the way in which the characters might be influenced by models of behaviour embodied in certain well-known film actors, just as people sometimes admit to being influenced by books they have read or people they have met. Gruault made the choice of Danielle Darrieux, Jean Marais and Jean Gabin as the most likely ones to fit his three characters. Filming took place in Paris and on location at Cholet and the Îles Logoden in Morbihan, Brittany. The budget was not sufficient to allow extensive studio filming and so existing locations were used but often completely transformed (e.g. a bank became the broadcasting offices). The fictional stories were filmed in advance and independently of Laborit's contributions. At this stage Resnais did not know exactly what Laborit was going to say, although he had discussed with him the general themes which he would cover. Some very long shots were filmed in the stories to allow flexibility for Laborit's words to be added later. The editor Albert Jurgenson commented that the role of the editing process in the film was more important than usual, and the various elements were so complex that everything could not be foreseen in the planning; the film was thoroughly rebuilt at the editing stage. In the film's epilogue a montage of travelling shots shows a landscape of abandoned and half-demolished buildings in the Bronx, New York, culminating on a starkly contrasted mural of a green tree painted on the side of one of the buildings, providing a moment of relief and pleasure. The camera then moves progressively closer to the mural in a series of shots, causing the whole image to disintegrate into its constituent parts until we can see only fragments of paint on the side of a single brick.