Book excerpt: This book tries to re-read the American dramatist Eugene O'neill through one of his most powerful plays: Long Day's Journey Into Night. It is a new approach of this playwright and his philosophy as it is deeply dramatized via two dimensions.That is to say, the autobiographical presence of O'neill in the play and the psychological traumas which he went through in his life. In the same path of Doris Alexander, Normand Berlin and other eminent figures who have worked on O'neill's art, I try to offer in this study a vivid descritpion of the Strindbergian effect on American Drama in the first half of the twentieth century as this theme is highly dramatized in O'neill's Long Day's Journey Into Night which offers a landmark and a real turning point in the history of western theatre in general.