Music provides us with the illusion that we are able to escape from time. Notation and recording are time-based. The author discusses the complex relationship that the composer has with time: between differed-time and real-time. He also explains why some performers want to control the speed of a tape and how they can do it with the GROOVE and 4X systems. But real-time is not a panacea. Risset upholds that live electronic works cannot access to the complexity of a tape complexity.