In 1977, Edgar Morin published the first volume of his great work, The Method, in which he explained in detail his fundamental concept of “complexity.” In 1983, he wrote the third volume, but lost it, and went on to publish volumes 4 through 7, the last of which was published in 2004. But the lost manuscript has now been found, the real volume 3 that Actes Sud is publishing today with a historical recontextualization.