A Case of Conscience is a first-contact novel where the humans arrive, find the perfect alien society, and the priest on the team decides it has to be a trap. James Blish published it in 1958 through Ballantine, and it took the 1959 Hugo for Best Novel at the Detention in Detroit. Hardly any science fiction of the time tried religion at all, and fewer still tried Catholicism from the inside, which is a big part of why the book stuck.
It started life as a novella in the September 1953 issue of If, which is the first section of the finished book. Blish added a second half in 1958 that moves the whole thing back to Earth, and the two halves read like different books. One is a careful, tense argument on an alien world. The other is a satire, a riot and a very large explosion.

Lithia
It’s 2049. Father Ramon Ruiz-Sanchez, a Peruvian Jesuit, is one of four scientists sent to the planet Lithia to decide whether it should be opened to human contact. He’s the team’s biologist and biochemist, and he doubles as the doctor. He’s also a priest, which means he’s the only one of the four who’s worrying about souls.
The Lithians are intelligent, bipedal and reptilian, and Ruiz-Sanchez is the one who bothered to learn their language. What he finds is a society with no crime, no politics, no want and no religion. Their ethics line up with Christian ethics point for point, and they get there by pure reason. There’s also no sign they ever needed a god to reach any of it. Their technology is far ahead of what their iron-poor planet should allow, including a planet-wide communications web driven by pulses from a giant Message Tree whose roots run down into the bedrock.
The team is Ruiz-Sanchez, Mike Michelis the chemist, Agronski the geologist, and Paul Cleaver the physicist. Early on a plant poisons Cleaver through his protective suit, and Ruiz-Sanchez treats him. He’s also on his way to message the others when his Lithian friend Chtexa invites him home, which no human has been allowed to see before. The house, the family and the calm of it all knock the wind out of him. Chtexa tells him things about Lithian life that Ruiz-Sanchez files away and doesn’t like.
The vote
The team gathers to write its recommendation, and it splits four ways inside one room. Michelis, who has picked up the language and a lot of the customs, wants Lithia opened. Agronski is easygoing about it. And Cleaver, once he’s back on his feet, wants to exploit the place whatever the Lithians think, because the planet is sitting on pegmatite, a lithium source, and lithium is what Earth needs to make deuteride for its bombs. His plan, as the story lays it out, is to close Lithia publicly and quietly turn it into a weapons lab.
Ruiz-Sanchez votes to close the planet too, but for the opposite reason. He’s become convinced that Satan built Lithia on purpose, as a showpiece proving that peace, logic and decency can exist with no God in the picture, and that if Earth sees it, faith will take the hit. He lists the facts against Catholic teaching one at a time. Michelis doesn’t follow him, but he does point out that all the Lithian science he’s learned rests on assumptions that are logical and strangely baseless, as if the whole structure just showed up from nowhere. The two votes for closure come from men who couldn’t be less alike, and the other two vote to open it. Tie. Lithia stays off limits, for now.
As the humans leave, Chtexa gives Ruiz-Sanchez a farewell gift, a sealed jar holding a fertilized egg. It’s Chtexa’s own child, to be raised on Earth. Ruiz-Sanchez already knows the thing is a problem. Lithian young inherit what their parents know through their genes, so this egg isn’t a baby, it’s an entire adult culture folded into a seed. Around the same time he cracks a riddle from Finnegans Wake that has been nagging him, a question about marital morals ending “Has he hegemony and shall she submit?”, where Catholic teaching can’t accept a plain yes or a plain no. He sees it’s two questions, so the answer is “yes and no.” And then he goes home carrying a sealed jar.
Egtverchi
Part two drops us into a United Nations lab in New York. The egg hatches, the child is named Egtverchi (the name is written in his genetic code), and he grows up in months. Ruiz-Sanchez was right that he’d turn out to be a sentient being with the standing to become a naturalized UN citizen, and that’s where the trouble starts. Egtverchi becomes a television star and a razor-tongued satirist of human society.
Earth in 2049 is a shelter economy, with most of the population living underground in the shadow of nuclear war, and the damage shows. Egtverchi’s biggest audience is made up of the psychopaths that kind of life breeds, and he’s firecracker-in-an-anthill material. The Lithians were never built for a place like this, and he knows exactly which buttons to push.
Meanwhile Ruiz-Sanchez has to answer to Rome. Calling Lithia a creation of Satan is close to Manichaeism, so what he’s been telling people is heresy. He gets an audience with the Pope himself, a sharp and technologically aware Norwegian, who points out two things the priest had missed. One, Lithia might be a deception rather than a creation. And two, if Ruiz-Sanchez believes it’s an infernal trap, he could have done something about it: performed an exorcism on the entire planet. The embarrassing part is that Ruiz-Sanchez had been so lost in Joyce, a book he comes to see as 628 pages of compulsive demonic chatter, that the obvious answer never crossed his mind. The Pope sends him off to work on his own soul.
As a last attempt to reach Egtverchi, Ruiz-Sanchez takes him to a Canadian retreat run by Count d’Averoigne, a solid-state physicist who has built a device for talking in real time with the Message Tree. Egtverchi won’t listen to his Lithian father, and then comes worse news: Cleaver is back on Lithia running his weapons project, and he’s chopping down the Message Tree. Egtverchi makes one more broadcast and it sets off riots. The UN moves to arrest him. He stows away on a starship bound for Lithia.
The ending
Ruiz-Sanchez, Michelis and lab director Liu Meid join d’Averoigne at his observatory on the Moon, where he’s built a telescope that sees Lithia in real time, skipping the speed-of-light delay by getting around normal space-time. Through the starship, d’Averoigne has warned Cleaver that his experiment might blow up the planet, and he’s afraid Cleaver is too stubborn to stop.
The screen shows Cleaver at work. Ruiz-Sanchez, watching, pronounces an exorcism over the planet. Lithia explodes, and the image blows out the monitor with it. Cleaver is gone, and so is Egtverchi, and so is Chtexa and everything Ruiz-Sanchez had come to admire. Blish refuses to say whether the prayer did it or Cleaver’s reactors did. A man who spent the whole book arguing that virtue can’t exist without God’s grace ends up with a dead friend and no way to know if he killed him.
Why it won, and where it sits
Ruiz-Sanchez is the reason the book works. He’s a scientist and a believer, he loves the Lithians, and he’s convinced they’re evil. Blish doesn’t let anyone off easy, and he writes the priest as a man, with doubts and bad judgment and a stubborn streak. In the foreword Blish said he’d set out to write about “not a body of faith, but a man”, and he printed the Church’s actual policy on contact with extraterrestrial intelligence: possibly no immortal souls, souls in a fallen state, or souls in a state of grace.
Not everyone bought the theology. The director of the Vatican Observatory, Br. Guy Consolmagno, said the book’s theology isn’t Jesuit theology, and the Encyclopedia of Science Fiction says Blish plays fast and loose with Catholic doctrine while still calling it one of the more sophisticated early attempts to take religion seriously in the genre. Reviewers of the day were split on the structure. Galaxy’s Floyd C. Gale called it uneven but trailblazing, and Anthony Boucher loved the opening and thought the later material lost its focus. Damon Knight put it among the ten best SF books of the fifties.
It’s the first book in Blish’s After Such Knowledge sequence, which carries on through Doctor Mirabilis and the paired novellas Black Easter and The Day After Judgment. The sequence asks whether chasing secular knowledge is itself a kind of evil, and Lithia is the first test of it. The book was also picked for the Library of America’s American Science Fiction: Nine Classic Novels of the 1950s, and Blish’s author page there has an essay on the novel from James Morrow.
This was a year with real competition, too. Poul Anderson’s The Enemy Stars (serialized as “We Have Fed Our Seas”) was on the same ballot, and you can see the whole slate on the Hugo Awards’ own 1959 page.
If you want the other great Catholic SF novel of the same decade, my post on A Canticle for Leibowitz takes the Church through nuclear collapse instead of out to the stars, and it won the Hugo two years after this one. For another book that runs a whole sandbox of religion and ecology through a single hero’s choices, there’s Dune. And if you want to see how far the early Hugo list swings, The Demolished Man is a murder mystery where telepathy turns the whole genre inside out, and the Hugo list jumps from that to Starship Troopers next.
For a plot summary from another angle, EBSCO’s research starter on the novel covers the same ground with a different emphasis on the Lithian side.