Blish was well read in theology, philosophy, and literature, and the precedents for the moral and theological discourse which underlies A Case of Conscience may be sought in innumerable medieval and modern texts. A discussion of the background to the Manichean Heresy alone would take a fulllength article. The problem of the good nonbeliever has been a source of much agonized soul searching for the church since its earliest days. Much time was spent discussing whether or not such people could be saved, during their lifetimes or retroactively; Dante's use of Virgil in The Divine Comedy might serve as a useful gloss on this subject, as would the medieval Saint Erkenwald.

Serious discussion of religious issues is rare in science fiction but several memorable treatments can be mentioned, especially Arthur C. Clarke's "The Star" (1955), in which another priest-scientist, a member of a party exploring an ancient...