Shaw himself provides the best guide to the thematic concerns of Saint Joan in his preface to the play. See the "Summary and Analysis" section for a detailed discussion of the preface; this section will highlight three of the major themes that Shaw mentions in the preface and will give some indication of how he develops those themes in the play itself.
Joan as a Hero of the Imagination. When Shaw invokes the "imagination" in reference to Joan, he does not mean that Joan was consciously "making up" the voices and visions she experienced, or that, as her accusers state in Scene VI, that she was "pretending" to receive messages from the saints. Rather, Shaw means that Joan possessed a faculty for transcending the everyday concerns of most people; she was gripped by, shaped by, driven by what Shaw calls the "evolutionary appetite" for humanity's advancement to a degree that most people are not. She is a "visualizer." Shaw's conviction on this point accounts for the several references to imagination in the play (for example, Baudricourt's "They come from your imagination," Scene I; "Must then a Christ perish in torment in every age to save those that have no imagination?," Epilogue). For Shaw, the imagination is the source of humanity's progress, and Joan is one of its strongest representatives. In this respect, and not in the traditional ecclesiastical sense, Joan is, for Shaw, a "saint." She is "the unaveraged individual, representing life possibly at its highest actual human evolution and possibly at its lowest, but never at its merely mathematical average." She is "upstart" in the positive sense of the word-but also in its negative sense, which, in Shaw's view, ultimately leads her to her doom.
The Will to Power. In his preface, Shaw points to the major social and cultural forces of the Middle Ages-the church and feudalism-as rocks against which Joan, in her innocence and naivet, was dashed. Throughout the play, but especially in Scene VI, Shaw depicts Joan as someone who does not understand the powers she is up against; a victim of a collision between various peoples' quest for and use and abuse of power. Thus the Archbishop can warn Joan, in Scene II, that it is dangerous to be "in love with religion"; and thus, for another instance, the Inquisitor can state, after her trial is concluded in Scene VI, "[I]t is a terrible thing to see a young and innocent creature crushed between these mighty forces, the Church and the Law." Cauchon tells Warwick in Scene IV, "I know well that there is a Will to Power in the world. I know that while it lasts there will be a struggle between the Emperor and the Pope, between the dukes and the political cardinals, between the barons and the kings. The devil divides us and governs." To a large extent, Shaw's characters serve as ciphers for the powers they represent, and the conflicts between them on stage dramatize larger, more abstract conflicts among these powers. Notably, Joan, who represents the "super-personal" (that is, concerned with more than the individual) power of the evolutionary appetite, is destroyed by these conflicts.
Perspective. Shaw stresses that those who would understand Joan must understand the world in which she lived. In the play, Shaw attempts to create this perspective for his audience by granting his characters a self-awareness they did not possess in real life. For example, in Scene IV, Warwick can identify Joan's doctrine of God's authority over the feudal system as "a cunning device to supersede the aristocracy"; or, in Scene II, the Archbishop can speak of miracles very pragmatically as "very simple and innocent contrivances" by which faith is created and bolstered. The Epilogue is also a dramatization of historic perspective, as the fifteenth and twentieth centuries mingle when The Gentleman appears to announce Joan's canonization. Shaw provides his characters with this perspective on themselves so that his audience will maintain a proper perspective of themselves, and will not judge the medieval subjects of his play too harshly: as Shaw repeatedly states in the preface, the twentieth century was no less superstitious and intolerant, and in some ways more so, than the fifteenth.