The story of the Fall from Grace is central to Western civilization. Adam and Eve, the serpent, the tree of forbidden knowledge, these are cultural icons of overwhelming significance. The Fall is so important that its power as a symbol is virtually divorced from any actual belief in the literal truth of the Bible. Since the Middle Ages, and especially since the Renaissance, many writers have considered the possibility that scientific knowledge might also be dangerous, might in fact provide a temptation to sin comparable to that found in the story of Eden. Christopher Marlowe's Doctor Faustus and Mary Shelley's Frankenstein are two of the most famous such stories. Any discussion of James Blish's A Case of Conscience must occur within this context.

1.Unlike many of the major science fiction writers of his era, James Blish was sincerely religious. In A Case of Conscience, it seems...