An eight-part serial running about 12 and a half hours, this 1971 comedy drama is Jacques Rivette’s grandest experiment and most exciting adventure in filmmaking. Balzac’s History of the Thirteen, about a few Parisians who hope to control the city through their hidden interconnections, inspired its tale, dominated by two theater groups and two solitary individuals. Some of the major actors of the French New Wave participated (Juliet Berto, Francoise Fabian, Bernadette Lafont, Jean-Pierre Leaud, Michel Lonsdale, Bulle Ogier), creating their own characters and improvising their own dialogue, and Rivette juxtaposes their disparate acting styles; acting exercises dominate the first episodes (including one 45-minute take) until fiction gradually and conclusively overtakes the documentary aspect. What emerges is the definitive film about 60s counterculture: its global and conspiratorial fantasies, its euphoric collective utopias, and its descent into solitude, madness, and dissolution. Out 1 has always been the hardest of Rivette’s films to see, so this screening, spaced over two days with breaks for food and rest, is a major event. Reviewed this week in Section 1. a Sat 5/26, 2:30 (episodes 1 and 2) and 7 PM (3 and 4), and Sun 5/27, 2:30 (5 and 6) and 6:45 PM (7 and 8), Gene Siskel Film Center.