Historical studies of how myths and symbols change have only recently begun to emerge. They tend to stress the layered and historically stratified nature of myths, each stratum reflecting the concerns of an epoch or a particular group. Marina Warner (1982) has shown how the image of Joan of Arc has been differently interpreted by Nazis, nationalists, and feminists, among many others, and Jacques Le Goff (1980) has demonstrated how ecclesiastical and popular images of Saint Marcellus of Paris came to resemble each other but ultimately always remained apart. James Watson's stimulating study (1985) of Tian Hou, or the empress of heaven, argues that the outwardly unitary symbolic character of the goddess Tian Hou concealed important differences in what various social groups believed about her. Pioneering as they are, these works are only the start of efforts to probe the enormously complex relationship between change in the symbolic realm and historical change among social groups and institutions.