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->''"The idea of other planets exercised upon me then a peculiar, heady attraction, which was quite different from any other of my literary interests. Most emphatically it was not the romantic spell of ''Das Ferne''. "Joy" (in my technical sense) never darted from Mars or the Moon. ... I may add that my own {{planetary romance}}s have been not so much the gratification of that fierce curiosity as its exorcism. The exorcism worked by reconciling it with, or subjecting it to, the other, the more elusive, and the genuinely imaginative, impulse."''
-->-- '''Creator/CSLewis''', ''Surprised By Joy''

Everybody and their dog knows about [[Literature/TheChroniclesOfNarnia Narnia]], and has probably read it. They also probably know about the likes of ''Mere Christianity'' or ''TheScrewtapeLetters''. But if you ask them whether they realized that Creator/CSLewis wrote science fiction, they'll look at you like you're [[IncrediblyLamePun from another planet.]] ''The Space Trilogy'' is the unofficial name of his series of PlanetaryRomance and {{Fantasy}} novels, mixing space travel with Medieval cosmology and Christian theology.

The first, ''Out of the Silent Planet'', is a tribute to early science-fiction of the likes of ''From The Earth to the Moon''. Philologist Elwin Ransom is kidnapped by the (evil) scientists Devine and Weston, and taken in their space-ship to the planet Malacandra (or UsefulNotes/{{Mars}}, as we call it) as a human sacrifice to appease the natives while they mine the place for gold. He escapes, locates and falls in among the civilized natives (the otterlike ''hrossa'') and learns their language and their ways. He is then summoned to see Oyarsa, the ruler of of Malacandra. This being is an ''eldil'' -- basically, an angel -- and actually just wants to talk. In the court of Oyarsa, Ransom learns much of the history of ''eldils'' and the solar system, and the reason why Thulcandra (the titular Silent Planet, that is, Earth) has heretofore been cut off from the Heavens. Weston and Devine reappear, and their ultimate villainous goals are laid bare and [[{{Deconstruction}} dissected]]. Oyarsa then sends the three humans back to Earth.

In the second novel, ''Perelandra'', also known as ''Voyage to Venus'', it is revealed that the ''eldils'' have kept in contact with Ransom since his trip to the Heavens, and now Ransom has been given a [[MissionFromGod Mission From Maleldil]] to visit [[UsefulNotes/{{Venus}} Perelandra]] (i.e. Venus). He finds the planet to be covered in oceans and floating islands, and its inhabitants living a literally Edenic existence. Ransom makes the acquaintance of the planet's Queen, and discovers that she and the King (who has been missing for the past few days) are the only intelligent inhabitants. The peace is shattered by the arrival of another space-ship, bearing Weston--and [[DemonicPossession with him]], an ''eldil'' of Thulcandra, bent on corrupting this young world. Ransom realizes that he was sent to Perelandra to prevent this from happening--by [[GoodAngelBadAngel words]], and if necessary, by [[DidYouJustPunchOutCthulhu force]]. As a side-note, this was Lewis' personal favorite of everything he wrote.

The third novel, ''That Hideous Strength'', is a genre shift. (It's subtitled "A Modern Fairy-Tale For Grown-Ups" for a reason). In the quiet town of Edgestow, Jane Studdock finds herself haunted by strange dreams of a decapitated man and an undead mystic. Meanwhile, her husband Mark is strong-armed into joining the National Institute of Co-ordinated Experiments, a joint political-(quasi)scientific organization that is surreptitiously taking complete control of the town. The NICE is particularly interested in Bragdon Wood, where Merlin is rumored to be buried--not dead, just resting. With great reluctance, Jane falls in with the oddly inactive resistance led by Elwin Ransom--the only opposition to the NICE's (literally) diabolical plans.

If you get the feeling that this one is a hackjob copy of ''[[Literature/NineteenEightyFour 1984]]'' or ''{{Fahrenheit 451}}'', [[SeinfeldIsUnfunny you actually have it backwards]]. This book came first: and right about the time of the atomic bomb. George Orwell actually wrote a snazzy review (titled "The Scientists Take Over") and sang the book's praises, with the caveat that he thought it was weakened by the book's supernatural premise, since of ''course'' good will beat evil if angels are involved. The book is also riddled with Christian allegory, although less overtly so than ''Perelandra'' was. Slightly. Perhaps it may be most generously summed up in the words of Lewis's friend and fellow Anglican apologist, DorothyLSayers: "less good but still full of good stuff." On the other hand, another friend, Creator/JRRTolkien, dubbed it "That Hideous Book".

There is also an unfinished novel titled ''The Dark Tower'' (not to be confused with [[Franchise/TheDarkTower the Stephen King series of the same name]]) originally intended as a sequel to ''Out Of The Silent Planet'', and abandoned in favor of ''Perelandra''. The plot, in which Ransom was only a secondary character, involved an AlternateUniverse rather than space travel. Walter Hooper, the executor of Lewis' literary estate, published the fragment posthumously. The scholar Kathryn Lindskoog challenged the authenticity of ''The Dark Tower'', and accused Hooper of forging it--though this seems to be the minority view among scholars of Lewis.
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!!This series provides examples of:

* AdamAndEvePlot: ''Perelandra'' is rather explicitly a rehash of the Garden Of Eden (with Ransom as a GenreSavvy observer).
* AgentScully: [=MacPhee=], a die-hard atheist scientist, remains implacably skeptical throughout all the supernatural events of ''That Hideous Strength,'' even though he's on the side of the supernaturalists.
* AlienGeometries: Ironically, on Earth. The N.I.C.E. attempts to break Mark Studdock's mind by placing him in a room whose every proportion is ''off'' just enough to be noticeable but not enough to be obvious.
* AlienNonInterferenceClause
* AlienSky: The skies over Perelandra are opaque, leading to pitch black nights.
* TheAllegedBoss: Jules is nominally the director of N.I.C.E., but he's only a pompous windbag who's clueless about what really goes on there. Wither and Frost are actually in charge.
* AlmostOutOfOxygen: Carbon dioxide poisoning becomes an issue during the return trip in ''Out of the Silent Planet''. The characters move and speak as little as possible in order to reduce their respiration.
* AmbiguouslyGay: "Fairy" Hardcastle. She's definitely butch, but her lesbianism is implied rather than stated outright. Comes across like a more discreet version of the the GirlsBehindBars butch jailer stereotype.
** It's likely that Lewis wanted to depict a lesbian, but had ''no'' idea what a lesbian actually is; so, like many other writers, he took the [[IncrediblyLamePun cop-out]] route of putting a macho man into a woman's body and hoping that his readers wouldn't know the difference either.
*** Some readers think that Fairy Hardcastle was the "evil" counterpart to Dr. Grace Ironwood - another decidedly "mannish" woman who was also decidedly good.
** Alternatively, Lewis wanted to depict lesbians as being as evil as possible. Lewis had particular problems with women who looked or acted like men, as revealed in his other works. At the same time, he was too offended to actually portray sexual activity between two women.
* AnimalTesting: One of the many activities that goes on at N.I.C.E., usually involving vivisection. Nobody seems to really know ''[[ForScience why]]'' they're doing it.
* AscendedToAHigherPlaneOfExistence: [[spoiler:Ransom]] at the end of ''That Hideous Strength,'' at least thematically. He will never die, but will instead be transported bodily to Perelandra, where he will live in paradise forever. It's also implied that this happened to Enoch, Moses and Elijah... and King Arthur
* AuthorAppeal: Based on some of his private letters, Lewis might be suspected of this in the case of Miss Hardcastle.
* AuthorTract: The novels are as much philosophical exercises as they are stories. Again, par for the course when reading Lewis.
** ''Out Of The Silent Planet'' is a fictionalized version of Lewis' essay "Religion and Rocketry", describing how extraterrestrial life could be reconciled with Christian theology. See also the Deconstruction note below.
** ''Perelandra'' transplants the Garden of Eden to Venus, and raises the question of why the ForbiddenFruit was forbidden in the first place.
** ''That Hideous Strength'' is a fictionalized version of Lewis' ''The Abolition Of Man'', arguing against Philosophical Naturalism masquerading as Scientific Progress.
* AwesomeMomentOfCrowning: The King and Queen of Perelandra.
* BabiesEverAfter: What else should happen when Venus gets involved?
** When the escaped animals that were used for vivisection rendezvous at St. Anne's and proceed to do ... what animals inevitably do when presented with the opportunity
* TheBaroness: "Fairy" Hardcastle, head of N.I.C.E. security. It's strongly implied that she's a literal sadist who gets aroused by torturing female prisoners.
* BearsAreBadNews: A bear named Mr Bultitude kills the BigBad, who had kidnapped him from the zoo and used him for vivisection experiments. Hence also:
** ExitPursuedByABear: Mr Bultitude is a more-than-usually literal example.
* BigCreepyCrawlies: Ransom briefly encounters giant flies and beetles in the caverns under Perelandra. Subverted, however. Once the Un-man's presence is removed, and the fear it generated is gone, Ransom also ceases to fear the creepy crawlies, and speculates that they may, in fact, be sentient beings.
* BlueAndOrangeMorality: Merlin, although ultimately on the side of good, doesn't really fit within the modern framework of good and evil. One of the better examples of DeliberateValuesDissonance.
** This is actually a plot point in the story; one of the reasons that the protagonists wish to locate Merlin is because he lived in a time when practicing magic was acceptable. This allows them the luxury of having magic abilities on their side despite the such things normally being forbidden in the modern era as witchcraft. Merlin is basically an ethical loophole.
* TheBluebeard: How a newspaper refers to François Alcasan, who murdered his wife.
* BoomerangBigot: In ''That Hideous Strength'', [[ButchLesbian Miss Hardcastle]] is said to have once been a fascist. The fascists were virulently homophobic even for their time, and were ''very'' gung-ho about traditional gender roles. It's possible that Miss Hardcastle [[YouAreWhatYouHate simply didn't realize she was a lesbian then]], but Lewis never addresses the point either way.
* BuffySpeak: In ''That Hideous Strength'', [=MacPhee=] accuses women in general of talking this way and somehow still understanding each other.
* CallARabbitASmeerp: Maleldil, i.e. SpaceJesus.
* CannotTellALie: When Ransom tries on Perelandra, it is physically painful for him because the planet's purity abhors it. [[DemonicPossession Weston]] seems to have no problem with it though.
* CaptainErsatz:
** Weston and Devine are a darker version of Cavor and Bradford from Creator/HGWells' ''Literature/TheFirstMenInTheMoon''. Lewis himself was a fan of the novel.
** Ransom himself is explicitly based on Creator/JRRTolkien -- he teaches the same subject at Cambridge that Tolkien taught at Oxford. (Although in the third book, he seems more like Creator/CharlesWilliams). Tolkien was on the record as saying that he didn't think it was a very close resemblance, although he did recognize some of his own ideas "Lewisified" in Ransom.
** Horace Jules, the nominal director of NICE in ''That Hideous Strength,'' is a venomous caricature of H.G. Wells.
** [=MacPhee=], an Ulster rationalist and SarcasticDevotee from ''That Hideous Strength'', may have been a fictionalized version of Lewis' old tutor William Kirkpatrick. Or possibly an AuthorAvatar of Lewis himself, from his days as a skeptic.
*** The author says that [=MacPhee=] is pretty much Kirkpatrick; right down to his phrasing.
* ChicAndAwe: Implied in Jane Studdock's [[spoiler:pending reunion with Mark]] at the very end.
** More accurately describes her first meeting with the Director (Ransom)
* CloserToEarth: Mark is entirely taken with the Progressive Element and goes in with them almost immediately. Jane has a bad feeling about them.
* CloudCuckooLander: Again, the tramp.
* ColdSleepColdFuture: Merlin's experience of the modern world.
* TheCorrupter: the Un-man again, whose explicit mission is to recreate the Fall of Man with the Perelandrans.
* CrapsackWorld: Sulva, aka the Moon.
** Well, the part of it that faces towards us, and thus is part of our Fallen world. The other half is apparently pretty wonderful.
* CunningLinguist: Ransom.
* CurseOfBabel: The undoing of the NICE.
* DarkerAndEdgier: ''Perelandra'' has a considerably darker plot than ''Out of the Silent Planet'', with more at stake. ''That Hideous Strength'' is even darker.
* DarkIsNotEvil: In ''Perelandra'', inhabitants of Perelandra (Venus) undergrounds appear briefly. They are human-like and not evil, but not necessarily friendly to humans.
* {{Deconstruction}}: In ''Out Of The Silent Planet'', Weston's motivation for the colonization of Mars is the survival of the human race, even if this means killing all the natives of Mars. Or killing any humans who stand in his way. The conversation with Oyarsa picks this philosophy to pieces. This aspect was most likely intended by Lewis as a rebuttal to Olaf Stapeldon's novel ''Last And First Men'', which (arguably) condoned the genocide of native Venusians as necessary for humanity's survival.
** Lewis also deconstructs various popular human fears as found in science fiction. For instance, the notion that aliens -- particularly aliens stronger and smarter than us -- must necessarily have natures [[CosmicHorrorStory anti-thetical to and hostile towards human beings]]. In point of fact, each alien species is more similar to humankind than they are different -- even the EnergyBeings, who are the most different and powerful by far, love humans more than humans love each other. If there are legions of fallen eldil who plague humanity, it's simply because they ''choose'' not to live in peace with us.
* DeliberateValuesDissonance: Merlin in ''That Hideous Strength'' has a very alien mindset compared to the 20th century characters.
* DemonicPossession: The undoing of Weston.
* DetonationMoon: Will be Sulva's ultimate fate.
* TheDevilIsALoser: Or at least a disgusting sociopath. As in his earlier novel ''TheScrewtapeLetters'', Lewis was pretty intent on dissecting the idea of Satan as a suave MagnificentBastard and tried to portray him in ''Perelandra'' the way he thought a truly pure evil being would be like. Ransom comes to the realization that for demons, intelligence is a trait that they can put on or remove at will--it's like clothes they wear rather than an innate characteristic. And based on the Un-Man's petty behavior whenever he isn't "working", it's clear he would rather be intelligent as little as possible. At one point, Ransom even specifically thinks that he would much rather face a Mephistopheles-type of demon than the thing he has to put up with.
** Lewis also wanted to make the point that, having renounced the source of all good, Satan has to renounce all good things, intelligence being one of them. His philosophical/ontological position is inherently insane, like a man sawing off a tree limb he's sitting on.
* DidYouJustPunchOutCthulhu: In ''Perelandra,'' Ransom has to take out evil incarnate with no other weapons than his fists. And he's a middle-aged professor without much fighting experience. [[spoiler: However, it happens that evil is currently incarnate in the body of another middle-aged professor, so it's a fairer fight than Ransom feared.]]
* DistractedByMyOwnSexy: * Subverted in ''Perelandra''when the Un-Man, in Weston's body, tries to teach vanity to the Green Lady by dressing her up in a feather-cloak and letting her see herself in a small convex mirror, but the experience fails to captivate her. Protagonist Elwin Ransom remarks to himself, "Thank God, he's only trying to teach her Vanity," invoking this trope as a might-have-been. The Lady eventually grows bored with looking at a small image of herself and returns to her normal activities. The trope is also flirted with in ''That Hideous Strength'', particularly when the ladies of Logres are dressing up.
* DrivesLikeCrazy: Hilariously, Dick Devine/Lord Feverstone. He runs over a chicken, and declares all the animals (and pedestrians) he misses "damned lucky".
* DystopiaJustifiesTheMeans: The N.I.C.E.'s eventual aim is Transhumanism, with mankind replaced with a new and "superior" form of life.
* EldritchAbomination: Even meeting the ''good'' EnergyBeings can be unsettling, but the evil ones certainly count. The fact is even pointed out that meeting a ''good'' Eldil is even ''worse'' than meeting a bad one. When faced with evil, one can still hope for the good to save you -- what do you do when a good Eldil is still terrifying?
* EnergyBeings: The ''eldils'' are essentially Christian angels, and some of them (the ones associated with a specific planet) are also the basis for the Olympian pantheon. They are imperceptible energy beings whose forms exist on a radically different wavelength than ours -- for them, gaseous matter doesn't exist, and liquids and solids are gaseous, so the planets of the Solar system are just clouds. To them, light itself is the water through which they swim, and the Sun is their wellspring. "Visiting" a planet means moving into one of those moving clouds and then keeping pace with its orbit to maintain the appearance of standing still, while using some sort of projection to interact with wispy, ephemeral creatures they cannot fully see (ie: ''us'').
* EvilCannotComprehendGood: Played straight with Professor Weston.
* EvilIsNotAToy: Weston learns this lesson in the hardest way possible. In the time between the first and second book, he consorts with demons while convincing himself that there is no difference between God and Satan, and they are merely two sides of the same all-encompassing spiritual Force. In his usual pompous fashion, he deliberately calls the Force into himself, at which point [[DemonicPossession his will is immediately subsumed by the devils]]. His last words as himself are utterly terrified.
* EvilIsPetty: The un-man on Perelandra. Capable of making very eloquent arguments to tempt his subject towards evil; but when he's unable to do anything more profoundly evil, he spends his time torturing small animals and playing childish pranks on Ransom.
** Arguably, Devine as well. In ''Literature/OutOfTheSilentPlanet'', while Weston and Devine are both evil, Weston is a deconstruction of the WellIntentionedExtremist who justifies his evil actions as necessary for the survival of the human race. Devine is only there for the gold; and Oyarsa describes him as a "broken" man whose only motivation is greed. As Lord Feverstone in ''Literature/ThatHideousStrength'', he's aware of the true nature of the [=NICE=]; but isn't interested in the supernatural aspects, his only motivation being personal power.
*** Oyarsa actually remarks in the first book that if it were up to him he would simply destroy Devine, as any humanity in him died a long time ago. Conversely, he would attempt to cure Weston.
* EvilutionaryBiologist: Professor Weston develops interplanetary travel so humanity and their descendants (whatever they evolve into) could go out into the stars and survive throughout the cosmos. However, Weston doesn't care that this plan may involve wiping out other intelligent life. (In the second book, he abandons this goal in favor of a New Age-y philosophy he dubs "Spiritual Evolution", which has nothing to do with this trope.) The trope is taken further in the third book, where the N.I.C.E. plans to improve organic life by mechanizing it to an unprecedented degree, removing all those annoying biological (and psychological) barriers to progress -- [[TheEvilsOfFreeWill like free will]].
* {{Expy}}: Ransom is largely inspired by Lewis' close friend Creator/JRRTolkien.
** Also, [=MacPhee=] is inspired by Lewis' tutor and mentor, William Kirkpatrick, a.k.a. The Great Knock.
* FaceRevealingTurn: Invoked. "Perhaps I should see a figure which looked like Ransom standing with its back toward me and when I spoke it would turn round to reveal a face that was not human at all...."
* {{Fictionary}}: The Old Solar tongue.
* ForbiddenFruit: In this [[TheVerse 'verse]], every planet's sapient inhabitants are given a single rule that is not to be broken. Earth's rule was the TropeNamer. Perelandra's denizens are not allowed to sleep on solid ground, and must return to one of the floating islands in the ocean. Lewis' conclusion seems to be that most of [[Literature/TheBible Genesis 3]] is merely window-dressing. It was the ''fact'' of Adam and Eve's disobedience that matters; the ''form'' it took (whether eating a literal fruit or sleeping on solid ground) is immaterial.
* AFormYouAreComfortableWith: In "Perelandra", two major eldila appear in human form, but it takes them some practice. See "Our Angels Are Different" below.
* ForScience: Filostrato, one of the N.I.C.E.'s more (relatively) idealistic members.
* FunWithAcronyms: The N.I.C.E. (National Institute of Coordinated Experiments).
** FridgeHorror: There really is a institute with the same acronym in the UK - the National Institute for Health and Clinical Excellence.
* TheGodsMustBeLazy: In ''Perelandra'', Ransom wonders why he wasn't receiving divine help in light of the direct demonic intervention from the other side. The answer: [[spoiler: God works InMysteriousWays. Ransom himself ''is'' the divine help -- Adam and Eve didn't have the benefit of advice from an older race that had failed the ForbiddenFruit test; Weston/the Un-man is Satan ''in the physical body of a human being'' -- which imposes certain physical limitations, and [[DidYouJustPunchOutCthulhu which can be killed]]...]]
* GoodAngelBadAngel: Ransom and the demon in ''Perelandra''.
* GoodIsOldFashioned: The view of Weston and the [=NICE=].
* GoodPeopleHaveGoodSex: "Venus at St. Annes'", the last chapter of ''That Hideous Strength.''
* GreenSkinnedSpaceBabe: The Queen of Perelandra, literally.
** Implied that, this being Venus, her race's blood is oxygenated by Copper rather than Iron
* HannibalLecture: Weston's speech to Oyarsa justifying his murder of the Malacandrans, as well as planned genocide and colonization of the planet. Thoroughly deconstructed, as noted elsewhere, to the point where Oyarsa's response effectively qualifies as an indirect ShutUpHannibal.
* HardOnSoftScience: "There ARE no sciences like sociology" says Hingest. And the "scientific" programs of the N.I.C.E. are depicted throughout as just a front for totalitarian scientism.
* HeroOfAnotherStory: Invoked, oddly enough, in regard to ''setting''. When Ransom finds himself in Venus' cave systems, he comes to the conclusion that the caves were certainly designed for some purpose... but that he has no place in them and that whatever the caves are made for, it has nothing to do with him.
* {{Homage}}: Over in the DCUniverse, the Martian word for "Mars" is "Ma'aleca'andra" as an homage to this trilogy.
* HumanAliens: The King and Queen of Perelandra. (Justified: since Maleldil chose the physical form of a human being, all sapient life younger than the human race looks like Earthlings.)
* HumansAreFlawed: Humans are the only intelligent species in the Solar System to be "bent", i.e. have a sin-tainted nature. This doesn't mean that humans are universally [[KickTheDog puppy-kicking]]-bad, but in spite of our technological superiority we don't have anything in particular to offer to the other people of the Solar System. They're all quite happy with their lives, and do not lie to, cheat, or murder each other.
** There's more to it than that. Residents of Malacandra have the occasional "bent" individual, but these are few and far between because the planet's Oyarsa - the angelic ruler - is still good. On Earth, not only are the people bent, the Oyarsa (Satan) is as well, so sin is unchecked.
* HypocriticalHumor: The officially modernist and egalitarian Jane is surprised and repelled to find that the only physician among the folk of Logres is a woman, Dr. Grace Ironwood, and that these folk make no class distinctions: Dr. and Mrs. Dimble regard themselves as on the same level, and members on the same terms, as Ivy Maggs, Jane's former charlady. Worse, they regard the charlady and her convict husband as on a par with Jane and Mark! (And at that, they are probably being generous, in their own minds. Mr. Maggs just stole a little money from the laundry where he worked before he met Ivy and [[LoveRedeems went straight]]. Mark is involved in an infernal conspiracy to take over the world, and Logres isn't yet sure if he's a dupe or a traitor.)
* IfJesusThenAliens: Explored in many ways. Both Jesus and aliens appear, but belief in the two is not necessarily linked.
* InterspeciesFriendship:
** In ''Out of the Silent Planet'', Ransom befriends Hyoi the hross.
** In ''That Hideous Strength'', friendship between she-cat and bear (rather normal ones) is shown.
* InWithTheInCrowd: Mark Studdock's motive for joining the NICE in ''That Hideous Strength''.
* ImAManICantHelpIt: Invoked by Weston. He sees Ransom with the (naked, as it's an Eden-ish paradise) queen of Perelandra and assumes Ransom was making a move on her. Ransom tries to explain that he was not, and that the whole planet is full of such innocence that he didn't even feel any lust and interacted as normally as he would have with anyone clothed on earth, but Weston just assumes that Ransom is lying since as a man standing with a naked women, he naturally ''must'' have been trying to make love to her. Also qualifies as EvilCannotComprehendGood.
* IronicName: The N.I.C.E. is not very nice at all.
* ItsAllAboutMe: Both Weston and Devine in ''Out of the Silent Planet'' have no regard for anyone but themselves, despite Weston's flowery rhetoric about advancing the human race. Oyarsa sends them and Ransom back to Earth, and informs them that their ship will be unmade after their land, along with anything and anyone left inside. Ransom is asleep when they land, and wakes to find that they left without bothering to wake him. He barely makes it out of the ship before it is destroyed.
* KickTheDog: The Un-Man, in its spare time, tortures small animals ForTheEvulz.
** The N.I.C.E. vivisects any animal it gets its hands on.
* KingInTheMountain: Merlin, resting under Bragdon Wood in ''That Hideous Strength''.
* LadyLand: The Pfifltriggi are matriarchal.
* LipstickLesbian: "Fairy" Hardcastle's inner circle minions are explicitly described as the sort of "fluffy, simpering" hyper-feminine stereotype. Like Miss Hardcastle, their lesbianism is implied rather than stated outright.
* LiteralMetaphor: When Mark's superiors at N.I.C.E. mention [[spoiler: "the Head", he assumes they're just talking about the person in charge. He finds out later that it's an ''[[LosingYourHead actual decapitated human head]]'', [[OracularHead and the ringleaders are taking orders from it]].]]
* LiteraryAgentHypothesis: Used in the epilogue to ''Out of the Silent Planet'' and introduction to ''Perelandra'', where it is suggested that the author is a friend of Ransom's, but dropped for the third book.
** Well, sort of dropped. Lewis gives a first-person description of his own fictional visit to Bragdon Wood, thus giving himself a toehold in the story. On the other hand, it's hard to see how Lewis-as-character could have learned about a bear's stream of consciousness or the last thoughts of the villains as their doom overtakes them. (On the third hand, one of the surviving characters IS clairvoyant, so maybe... Nah.)
* LosingYourHead: One of the experiments at N.I.C.E. involves attempting to keep a severed human head alive indefinitely.
* UsefulNotes/{{Mars}}
* MeaningfulName: Ransom, whom Maleldil compares to Himself, as He is "the ransom of the world". An interesting twist: Ransom, being a linguist, knows that his name isn't actually related to the word "ransom" -- but the evolution of his family name seems to be no accident.
** Also, "Elwin" means "elf-friend" in the Anglo-Saxon. Considering how much of JRRT's writings in the Inklings affected the Space Trilogy...
** Don't forget Frost and Wither, whose names reflect the effects of the N.I.C.E.'s psychological training on their personalities. Frost's mind was made cold, hard, and sharp, like ice. Wither, on the other hand, just sort of "withered" away. There's also Dr. ''Winter'' and Devine's title is Lord ''Fever''stone. Pretty much everyone at N.I.C.E. has a name that suggest the failure, absence or corruption of organic life ("Hardcastle" is possibly meant as another one.)
* MoralDissonance: Curiously enough, in-universe. Merlin is appalled by his wakers' hospitality even though he acknowledges that their technological advancements are very comfortable, because they replace servants who would honor him with devices that just sit there. In this and several other ways, he comes off as barbaric, both to the reader and to other characters. Justified, of course, in that Merlin is a superficially-Romanized Celt from hundreds of years prior.
* [[MostWritersAreWriters Most Philologists Are Philologists]]
* MulticulturalAlienPlanet: In ''Literature/OutOfTheSilentPlanet'', the inhabitants of Malacandra come in three different species (not counting the energy beings), each with its own language. Furthermore, the sorns (giant feathered humanoids) come in at least two varieties - white (in the mountains) and red (in the deserts), and the hrossa (otter-people) come in at least three races - black, silver, and crested. There might be more, but the viewpoint character wasn't on the planet long enough to tell, as he was vividly aware.
* NoHoldsBarredBeatDown: The duel between Ransom and Weston is horrendously violent, even more so when Ransom gets the upper hand. For a moment you think you're reading a Creator/MattStover novel.
* NoBiochemicalBarriers: ''Everything'' seems to be edible on both Malacandra and Perelandra. It may be a subtle implication that Earth having poisonous vegetation is one result of its occupation by [[OurDemonsAreDifferent evil]] ''[[OurAngelsAreDifferent eldila]].''
* NoSuchThingAsSpaceJesus: Inverted. This ''is'' C.S. Lewis, after all. The whole series is pretty much ''about'' Space Jesus.
* {{Planetville}}: Averted via LampshadeHanging in ''Out Of The Silent Planet'': as Ransom leaves Malacandra, he realizes what a tiny portion of the planet he actually saw.
* OlderThanTheyLook: By the third book, Ransom is extremely youthful in appearance despite pushing 50 and sporting a long, luxurious beard. Yet he also gives off an aura of wisdom befitting one much older. The former is from visiting Perelandra, the last truly paradisal world, and the latter is from his experiences making him ''truly'' humble - that is, having no illusions about his true nature as a creature of [[{{God}} Maleldil]].
* OnlyKnownByTheirNickname: Ransom in the first book. This was retconned in the remaining two books to be his actual name.
* OurAngelsAreDifferent: Into GoMadFromTheRevelation territory. For instance, when two major eldila are unfamiliar with humans and need to practice appearing to them:
-->A tornado of sheer monstrosities seemed to be pouring over Ransom. Darting pillars filled with eyes, lightning pulsations of flame, talons and beaks and billowy masses of what suggested snow, volleyed through cubes and heptagons into an infinite black void. "Stop it ... stop it," he yelled, and the scene cleared. He gazed round blinking on the fields of lilies, and presently gave the eldila to understand that this kind of appearance was not suited to human sensations.
** This is similarity to angels' descriptions in Literature/TheBible, suggesting that in-universe they often have trouble with this (and explains the "Be not afraid" line as well).
* OurMermaidsAreDifferent: Ransom sees mer-people in the Perelandran ocean, and wonders if the green-skinned humanoid inhabitants of the planet might have have evolved from them.
* OutOfFocus: Ransom in the third installment. After his adventures in the first two books, he graduates from TheHero to the BigGood, and the story focuses on two new characters, Jane and Mark Studdock, and their conflicts with the N.I.C.E.
* OpposedMentors: An evil example where the two chief villains disagree on the best way to dehumanize their initiate/captive.
* PeaceAndLoveIncorporated: The N.I.C.E.
* PlanetOfHats: Descriptions of the three races of Malacandra tend to embody this trope.
** The Hrossa are warrior-poets and musicians prone to flamboyant action and speech; their humour consisting predominantly of [[JustForPun elaborate wordplays]]. They take great joy in hunting dangerous animals face to face, and composing epic poems; but are prone to overlook simple practicalities. Likely inspired by the style of the Scandanavian Literature/{{Edda}}s and [[Literature/TheIcelandicSagas Sagas]].
** They Seroni are reserved and solitary shepherds, whose humour is described as dry and sardonic. They're the philosophers and scientists, more interested in abstract principles than technology.
** The Pfiffltriggi are miners and artists; whose humour is described as "excelling in practical jokes and personal abuse". They are expert craftsmen and architects who delight in technology and the visual arts.
** Thulcandra and Sulva both have wickedness.
* PlanetaryRomance: Described by the author as such in the page quote.
* PoliceState: The college town, as ruled over by The N.I.C.E.
* PollyWantsAMicrophone: {{Discussed}} by Merlin when trying to prove Ransom's credentials.
-->''A [jack]daw that lives in a hermit's cell has learned to chatter book Latin before now. ... A daw may also have Greek on its bill.''
* ThePowerOfHate: The Un-man, being possessed by the devil, is pure evil-and Evil is the one and only thing in the universe that actually ''deserves'' hate. So Ransom realizes that he is justified in channeling his hate to help him [[DidYouJustPunchOutCthulhu punch out Satan]].
* PsychoLesbian: Again, Miss "Fairy" Hardcastle, who takes particular joy in torturing female prisoners.
* PurpleProse: The final chapters of ''Perelandra'' get downright rhapsodical. TropesAreNotBad, however, and some critics say that these passages of prose qualify as C. S. Lewis's best poetry.
* RealityIsUnrealistic: Invoked by the Pfifltrigg who carves Ransom's portrait. Ransom is alarmed that the final result looks very little like an actual human being, but the artist explains that he left out all but the most basic details on purpose.
-->''"I do not mean it to be too like. Too like, and they will not believe it -- the ones who are born after."''
* RubberyWorld: In ''Perelandra'', the eponymous planet has grasslands and forests that float on the surface of the ocean. A hill one moment is a valley another.
* SarcasticDevotee: [=MacPhee=], the only member of Ransom's TrueCompanions who doesn't share his Christian faith.
* ScaryShinyGlasses: Professor Frost was doing this way before [[Anime/NeonGenesisEvangelion Gendo]] made it cool. Even in a book, it's still scary.
* ScaleOfScientificSins: The N.I.C.E. follows just about the whole thing, almost to the letter.
* SceneryPorn: In ''Perelandra'', especially the mountain towards the end.
* ScienceIsBad: Some critics accused Lewis of arguing this, but WordOfGod clarifies that the villains are actually people who use the ''guise'' of science to promote inhuman philosophies. Notably, in ''That Hideous Strength'' the "real" scientist Hingest joined the N.I.C.E. because he believed it had something to do with science, and resigned [[spoiler: and got murdered for it]] as soon as he found it out it didn't.
* SecretPolice: The N.I.C.E. have their own police forces. They managed to seize control of a college town with only a handful of people realizing it.
* SeeminglyProfoundFool: The tramp. He gets mistaken for [[spoiler:Merlin]] by the N.I.C.E. and is either too simple or too smart to correct their mistake.
* ShoutOut: [[LordOfTheRings Númenor]] gets mentioned several times in ''That Hideous Strength'', based apparently on some discussions that Lewis had with Tolkien (Lewis apparently never saw a manuscript, since he invariably spells it "Numinor").
** Lewis also acknowledges his indebtedness to SciFi works such as ''Literature/TheFirstMenInTheMoon'' and ''Literature/AVoyageToArcturus.'' Not to mention the AdamAndEvePlot of ''Perelandra''.
** Meta-example: ''Music/IronMaiden'' has a song called "Out of the Silent Planet". [[LiteraryAllusionTitle Though named after the book]], the song was influenced more by the movie ''Film/ForbiddenPlanet''. Still, both works features a planet with a cosmic horrors causing great destruction ("The Monster from the ID" for Forbidden Planet, and the "Bent One" in the Space Trilogy).
** Similarly, ProgressiveRock band Music/KingsX has an album named ''Out of the Silent Planet''.
* SocialClimber: Mark started doing this while still in school, abandoning his genuine but tragically unpopular friend to be InWithTheInCrowd, unaware that they are basically working for Satan.
* SomethingCompletelyDifferent: ''That Hideous Strength''.
* SpaceOpera
* SquishyWizard: Merlin considers himself to be this.
* StarfishAliens: Malacandra has three alien natives, one looking like big intelligent otters, thin tall humanoids, and [[OurDwarvesAreDifferent tapir-headed frogish aliens]]. The Eldila, though obviously angels, are multidimensional energy beings who inhabit space itself.
* StealthPun ?: So stealthy I'm not sure it's there. The oblivious figurehead of the villainous N.I.C.E. is Horace Jules, a clear parody of H. G. Wells. Now, not only does his last name recall his contemporary SF author, Jules Verne, but if you pronounce "H. Jules" aloud, it sounds a fair bit like "H. Gee-wells."
** Also, Ransom turns to a poem about Germanic sound laws when things are looking [[http://en.wikipedia.org/wiki/Grimm%27s_law grim(m)]].
* TakeThat:
** H.G. Wells. Lewis was very much a fan of Wells' earlier fiction (he used the opening pages of the first book to essentially say that anyone who refuses to read ''War of the Worlds'' or ''The First Men in the Moon'' is being a snob), but was quite critical of the much more political and less well-remembered utopian novels Wells wrote later in life. (Elsewhere, Lewis compared Wells to Esau, saying that while Esau had sold his birthright for a mess of pottage, Wells had hocked his talent for a pot of message.) Hence, Horace Jules, the clueless pompous twit who is the figurehead Director of the NICE, looks and talks like a Wells parody.
** [=J.B.S. Haldane=], with whom Lewis carried on an open debate, is also targeted. Some of Weston's philosophy is almost word-for-word quotes of statements by Haldane. Haldane, in turn, wrote a rather scathing criticism of The Space Trilogy (which Lewis rebutted in the posthumously published essay "A Reply to Professor Haldane").
* TearsOfFear: When [[spoiler: Merlin]] realizes that RedemptionEqualsDeath. Also counts as InelegantBlubbering.
* TimeAbyss: Ransom's company gets a good dose of this trope when they feel the presence of the Oyarsa of Saturn.
* ToWinWithoutFighting: St. Anne's plans to win not by force, but relying on the ''eldil''. While [=MacPhee=] wants to use human might to defeat the N.I.C.E., Ransom and the others know that isn't an option. [[spoiler: They succeeded, with Merlin and the Oyeresu disrupting the Institute's plans]].
* TrippyFinaleSyndrome: The Great Dance vision at the end of ''Perelandra''. It's quite well done.
* UncannyValley: Described in-universe.
** Ransom is initially horrified by the appearance of the ''séroni'', because they're very elongated humanoids. The other two species of ''hnau'' on Malacandra resemble animals, so Ransom is able to accept them much sooner.
** He decides that thinking of the ''hrossa'' as anthropomorphic animals is a lot less unsettling than thinking of them as animalistic men.
** Subverted with the Queen of Perelandra. After he first sees her at a distance, Ransom briefly wonders if she's merely an animal that happens to look humanoid, a thought which disturbs him greatly. He soon finds out she's fully sapient.
** The "[=UnMan=]" ''looks'' human, but his behavior and mannerisms are just enough off to creep Ransom the hell out.
* UnusualEuphemism: In ''Literature/ThatHideousStrength'', "bucking" is used as a stand-in for...
* UtopiaJustifiesTheMeans: Says the N.I.C.E.
* WhatMeasureIsANonHuman: Subverted. The Old Solar language has a word for sapient creatures of any species: ''hnau''. Humans, Malacandrans, Perelandrans, and Eldila are all ''hnau'', and thus are all people. As an interesting twist, though, Lewis proposes that the human practice of keeping pets is an expression of our desire for companionship with people who are different creatures from us-the various Malacandrans find each other silly, amusing and refreshing. Humans talk to cats or dogs and treat them as family-members; a Hross goes to hang out with a Pfifltrig, who can actually talk back.
* WoundThatWillNotHeal: Ransom gets one on his heel on Perelandra [[spoiler:during his fight with the Un-Man]]. It stays with him throughout ''That Hideous Strength'' and gives him constant pain.
* YouNoTakeCandle: Weston has a poor grasp of Old Solar.
** See also Deconstruction. Weston gives a philosophical speech in English with some very stirring rhetoric; Ransom translates it into Old Solar, but he can only get across the basic ideas, not the rhetoric. The ideas ''are'' accurately conveyed, more or less, but stripped of their high-minded vocabulary they sound banal, if not outright barbaric; when Weston says that "Life itself is more valuable than any system of morality", Ransom flails around for an adequate translation before admitting that he cannot think of one.

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