Lee Strasberg was one of the major figures of American 20th century theatre, as teacher and artistic director of the Lee Strasberg Theatre Institute and the Actors' Studio. In this posthumously published legacy to the theatre, Strasberg explains the act of acting. Beginning with his own early experience and his discovery of the actor's central problem - achieving consistency of inspiration - Strasberg analyzes the work of the great Russian actor and director Konstantin Stanislavski, and describes how he and others added to that work to develop the system known as method acting.