Stanislavski's preparations for Maeterlinck's "The Blue Bird" (which was to become his most famous production to-date) included improvisations and other exercises to stimulate the actors' imaginations; Nemirovich described one in which the cast imitated various animals. In rehearsals he sought ways to encourage his actors' will to create afresh in every performance. He focused on the search for inner motives to justify action and the definition of what the characters are seeking to achieve at any given moment (what he would come to call their "task"). This use of the actor's conscious thought and will was designed to activate other, less-controllable psychological processes—such as emotional experience and subconscious behaviour—sympathetically and indirectly.