La part du hasard focuses exclusively on drawing and painting techniques used by the painter Henri Dimier. Shot over several weeks in the same artist's studio, the film shows works in their different phases, processes rarely explained or little known. It also addresses many practical issues (choice of paper, pigment grinding, reports drawings, put the tiles, cliches, etc) as well as broader questions of method and inspiration (use of space, the role of contours, power of suggestion perspectives, use of random processes). Patrick Bokanowski sought with this film to restore the spirit of this teaching, showing how to bend a note or sometimes revealing an essential mystery of creation.