Noting the importance to great actors' performances of their ability to remain relaxed, he discovered that he could abolish physical tension by focusing his attention on the specific action that the play demanded; when his concentration wavered, his tension returned. "What fascinates me most", Stanislavski wrote in May 1908, "is the rhythm of feelings, the development of affective memory and the psycho-physiology of the creative process." His interest in the creative use of the actor's personal experiences was spurred by a chance conversation in Germany in July that led him to the work of French psychologist Théodule-Armand Ribot. His "affective memory" contributed to the technique that Stanislavski would come to call "emotion memory".