the reader is now in possession of all the facts needed to determine what has happened to the aliens , and I hope not to be pointing out the obvious if I explain that the clue is in the apparent speeding-up of their television broadcasts . they do n&apos;t speed them up , which means , for instance , that when they walk around their space-ship they can change direction in something of the order of one-ten-thousandth of a second while moving at 30,000 miles an hour . no humanoid frame could stand that , unless its mass were very tiny . the aliens , then , are on the airfield all right , but their space-ship is sinking into a muddy heelprint or whatever . apart from the effects of awe and amazement produced by the description of the pulpy monsters and so on , what we have here is a strong puzzle interest that is widespread in science fiction as a minor aspect and not uncommonly central , as in this case . I have already mentioned the biological puzzle - problems of determining an alien life-cycle and the like - as an important sub-category ; another involves the question of finding the weak point in some apparently invulnerable monster or hostile alien or badly behaved human artifact of the robot sort . the solutions to these may be progressively revealed rather than shown as deduceable , but they need not be , and pictures do n&apos;t lie is not an isolated example of the approach that offers what are valid clues , even if they are only seen as such in retrospect . although interests of this kind can hardly be classed among the most lofty , it seems legitimate to call them as literary as any other . certainly science fiction appears to be on the point of taking over some of the functions of the traditional detective story , currently I believe in grave disrepair , though with a large audience , in England at any rate , nurturing itself on reprints and the more problem-posing kind of thriller . I can not believe that the Anglican parson and the Oxford classics don , those alleged archetypes of the Agatha Christie fan , would bring themselves to look through the files of astounding science fiction in search of a story like Isaac Asimov &apos;s little lost robot , but they would be the losers by their reluctance , for the science-fiction deduction problem , while to some tastes inferior to the detective story in its weaker connections with the world we know , is superior to that tiny motive-means-opportunity system in its range of both problems set and kinds of answer proposed . to take the commercial aspect : some partial merger between the publics of the two modes does seem eventually possible , as Anthony Boucher , the most level-headed of science-fiction commentators , foresaw some years ago . I have already mentioned the tendency of the more full-time writers to have a foot in both camps : Boucher himself doubles as the whodunit reviewer of the New York Times , and although I can not personally confirm his assertion that science-fiction elements have recently become perceptible in some detective stories , the opposite process is clearly under way . a recent story by Poul Anderson , the Martian crown jewels , gives us a brilliantly clever and inventive synthesis of the two media , with a Martian detective called Syaloch who affects a tirstokr cap , a locked-space-ship problem , and a completely fair presentation of clues ingeniously disguised as technological patter . even the most hardened Baker Street irregular would be captivated by the story - if he ever learnt of its existence . elsewhere , science fiction has been combined with what we are accustomed to distinguish as thriller or mystery ingredients rather than specifically deductive ones . all of these make some appearance in Chad Oliver &apos;s novel shadows in the sun . the problem here is why a small town in Texas consists entirely of recently arrived inhabitants and why these are all too average to be believable . this is soon explained - the hero boards a flying saucer on page 27 - but the first three chapters are stuffed with &apos;tec tricks of presentation and style , from verbless sentences and sinister single-sentence paragraphs ( he was afraid to go out or he had to know ) to the image of the hero , who is an anthropologist but tough - the ordinary science-fiction hero needs no such apology for his learning . this chap was a big man , standing a shade under six feet and pushing two hundred pounds . his brown eyes were shrewd and steady . he was dressed in the local uniform - khaki shirt and trousers , capped with a warped , wide-brimmed hat at one end and cowboy boots at the other . his Ph.D did n&apos;t show , and he did n&apos;t look like the kind of a man who had often been frightened , and as you might expect he soon takes up with Cynthia , who although fresh off the flying saucer makes good Martinis and is cool and slim and sets the hero &apos;s stomach feeling tight . these are recognisable as importations into science fiction , which avoids that particular kind of cheap-jack stuff and indeed deserves a small round of applause for not trying to expand its audience by concessions to salacity . a less inane ( and more recent ) example of attempted hybridisation is Richard Matheson &apos;s a stir of echoes , described on the wrapper simply as a novel of menace but in fact fusing science-fiction and &apos;tec elements with some show of wholeheartedness to produce a murder mystery with telepathic clues . the ability of a literary mode to expand into others is often taken as a sign of vitality , and it is true that between them fantasy and science fiction have gobbled up most of what was left of the horror story without much injury , but I can not feel that the injection of these thriller ingredients is likely to lead to much beyond blurring and dilution . it is not by capturing more territory that science fiction will improve itself , but by consolidating what it already has . such internal reconstruction would do well to start with an attempt to bring sexual matters into better focus . going easy on the puritanism would be a commendable resolve , and so would a decision to drop sex altogether where it is not essential rather than to decorate a planetary survey or alien invasion with a perfunctory love interest presented in terms borrowed from the tough school or the novelette . what will certainly not do is any notion of turning out a science-fiction love story . in the as yet unlikely event of this being well done , the science fiction part would be blotted out , reduced to irritating background noise - a dozen Venusian swamp-lilies being delivered to the heroine &apos;s apartment , and so forth . a recent effort , perhaps harmless in intention but unspeakable in execution , has been made to introduce a women &apos;s angle into the field , whereby we are introduced to a gallant little lady pretending to hate her man so that he can push off to Mars without pining for her , and an equally gallant little wife and mother uncomplainingly keeping up the production of tasty and nourishing meals while the hydrogen missiles are landing in the back garden . we can hope for more imaginative treatments than that , but the role of sex in science fiction as a whole seems bound to remain secondary . in the idea type of story it can have almost no place ; in the social utopia , it exceeds its warrant if it is much more than illustrative or diversifying , although one would not want to be decisive at what is still an early stage of the medium &apos;s development . to view with aplomb the prospect of continuing limitation of sex interest in science fiction is not the same thing as to accept a damaging poverty in it , for we are dealing with a genre , not a literature , and it is unnecessary to chide the Aeneid , for instance , on the grounds of its taciturnity about daily life in Augustan Rome . but I quite agree that almost nothing in contemporary science fiction is more calculated to affront the tiro , nor to raise more serious doubts of the medium &apos;s ability to come of age , than the horrid lyricism or posturing off-handedness which seem to be the regular procedures for handling these questions . similar doubts attend consideration of another , and I suppose , related , weakness in the medium as at present conducted : lack of humour and , far more than this , bad attempted humour . there is undoubtedly a kind of priggish pomposity which can afflict even the better writers , enough at times to subvert the moral tendency of what they are saying , and I connect this with the parochial circuit of mutual congratulation , leading in some cases to delusions of grandeur , in which most of them are involved ; this is a consequence , I feel , of the history and general circumstances of science fiction itself . as regards simple absence of humour , I like to think I &apos;m as fond of a good laugh as the next man , but I can stand doing without for long periods when reading , having been trained in the Oxford English school , and many of the best science-fiction stories , the xi effect , for example , distil a kind of horror hard to conceive of as harmonising plausibly with anything comic . some editors in the field , however , seem to have picked up from their reading the notion that humour is a sign of maturity , and compete with one another to fill their pages with stories whose very titles are enough to chill the blood : the cerebrative psittacoid , for instance , or the Gnurrs come from the voodvork out . there is even a whole mass of writing consecrated to the defeats inflicted on learned but hidebound scientists by a generic midwestern Paw and Maw of great natural wisdom ( alleged ) and hideous whimsicality ( actual ) . the British are not guiltless here either : a story called when grandfather flew to the moon married the concepts of space travel with traditional - that is , false and folksy - Welsh humour , introducing characters called Llewellyn Time Machine and Auntie Spaceship-Repairs Jones . this outstanding case of unwanted originality won a prize in the London observer &apos;s science-fiction contest , which seems to have been judged by non-addicts ; it has been reprinted , with squeals of editorial delight , in a leading American anthology . however , the picture as a whole is not as grave as this . humour as a main interest will sometimes work in this medium , provided that the comic notion is a valid science-fiction notion as well . one such example is William Tenn &apos;s satire on mediocrity , null-P ; others are to be found in the work of Sheckley , Pohl , and Fredric Brown . beside his contributions to the comic-inferno division in stories like a ticket to Tranai , Sheckley has devised a sub-form of his own , the comic problem . in the lifeboat mutiny , two men strive to outwit the mechanical intelligence which controls the boat ; it was programmed to meet the needs of an extinct , warlike , reptilian race and is of a verbose , officious disposition . finally the men sham dead and the lifeboat ejects them into the sea , having read the alien burial service over them . the comedy here arises from the characterisation of the non-human protagonist as it lectures the men on their patriotic duty , offers them food that looks like clay but smells like machine oil , and when they refuse it , threatens them with brain surgery . the solution to the problem , however , does not approach the theorematical neatness and cogency of that propounded in one man &apos;s poison . here , two other but similar men are starving to death in a vast , isolated alien warehouse filled with various outlandish goods , including food , poisonous substances , and a thing called the super custom transport , complete with fuel . the food turns out to be poison and so does the poison , whereupon the men settle down to dine off the super custom transport , which proves to be an animal , and its fuel , which is water . better than almost any other , this example of the science fiction of pure idea acts as a test case , in that those learned in the medium will at once salute its ingenuity and elegance , while those whose study is but little will complain of not being illuminated , of being offered an unworthy escape from the universe of man and fact , of being presented with a pseudo-question instead of a question . 