Three themes - impregnation, incarnation, dematerialisation - introduced by the colours blue, pink and gold, three colours defined by the artist as complementary and essential to his work, offer a key to entering the work of Yves Klein by insisting on subjects rarely touched on in previous publications: the anthropometric body prints, the sculptures, the utopian projects and his mastery of the video and photographic medium. The study also throws light on unexplored aspects of his work: his relationships with artists, his trip to the United States, and the perception of his work in its time in France and by American artists.