GUIDES TO ICONOGRAPHY AND SYMBOLISM
Butler's Lives of the Saints
Saints and Their Emblems
Saints in Art
Butler is the standard, classic source of biographical information on the principal saints. It is arranged by the saint's feast day. The other books describe how individual saints have been represented in works of art and are very helpful in understanding the scenes in which they are depicted.
Old Testament Figures in Art
Gospel Figures in Art
Retelling the stories of figures from the Old and New Testaments, these books are illustrated with full-color reproductions of art works to illustrate how these stories have frequently been represented in the visual arts.
Dictionary of Subjects and Symbols in Art
Dictionary of Symbols in Western Art
Symbols and Legends in Western Art
Handbook of Symbols in Christian Art
These books are exactly what they sound like, providing brief definitions for a wide range of subjects, themes, and concepts encountered in Western art. The last one concentrates on the symbols that appear in works of art with Christian subjects and themes, while the first three books also include symbols and subject matter drawn from Greek and Roman mythology, as well as cultural influences from other parts of the world.
Encyclopedia of Comparative Iconography
Iconographie de l'Art Chretien by Louis Reau
Iconography of Christian Art by Gertrud Schiller
The first of these books discusses both secular and religious iconography by broad themes or activities (e.g., envy or expulsion). The other two books are classics in the field of Christian iconography. Reau is in French, but even if your French is not that good, it is still worth consulting it. All three books deal with the variations and evolution of major iconographic themes. Bibliographical references and numerous illustrations are also provided.