A Case of Conscience

A Case of Conscience is a science fiction novel by American writer James Blish, first published in 1958. It is the story of a Jesuit who investigates an alien race that has no religion yet has a perfect, innate sense of morality, a situation which conflicts with Catholic teaching. The story was originally published as a novella-length "short novel" in the September 1953 issue of the If magazine. This novella won a Retrospective Hugo Award for Best Novella in 2004. In 1958, it was extended to a full-length-novel, of which the first part is the original novella. The novel, which won the Hugo Award for Best Novel in 1959, is the first part of Blish's thematic After Such Knowledge trilogy and was followed by Doctor Mirabilis and both Black Easter and The Day After Judgment (two novellas that Blish viewed as together forming the third volume of the trilogy).

Few science fiction stories of the time attempted religious themes, and still fewer did this with Catholicism.