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 in 1953, and later extended to novel-length, of which the first part is the original novella. The novel 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. Plot Part 1 In 2049, Father Ramon Ruiz-Sanchez of Peru, Clerk Regular of the Society of Jesus, is a member of a four-man team of scientists sent to the planet Lithia to determine if it can be opened to human contact. Ruiz-Sanchez is a biologist and biochemist, and he serves as the team doctor. However, as a Jesuit, he has religious concerns as well. The planet is inhabited by a race of intelligent bipedal reptile-like creatures, the Lithians. Ruiz-Sanchez has learned to speak their language to learn about them. While on a walking survey of the land, Cleaver, a physicist, is poisoned by a plant, despite a protective suit, and he suffers badly. Ruiz-Sanchez treats him and leaves to send a message to the others: Michelis, a chemist, and Agronski, a geologist. He is helped by Chtexa, a Lithian whom he has befriended, who then invites him to his house. This is an opportunity which Ruiz-Sanchez cannot decline; no member of the team has been invited into Lithian living places before. The Lithians seem to have an ideal society, a utopia without crime, conflict, ignorance or want. Ruiz-Sanchez is awed. When the team is reassembled, they compare their observations of the Lithians. Soon they will have to officially pronounce their verdict. Michelis is open-minded and sympathetic to the Lithians. He has learned their language and some of their customs. Agronski is more insular in his outlook, but he sees no reason to consider the planet dangerous. When Cleaver revives, he reveals that he wants the place exploited, regardless of the Lithians' wishes. He has found enough pegmatite (a