For the World is Hollow and I Have Touched the Sky ( episode ) The " Enterprise " finds an asteroid that contains a generational ship on a collision course with an inhabited planet . Summary . Teaser . The is attacked by primitive , chemical - fueled nuclear missiles . The crew of the " Enterprise " destroy the missiles with the ship ' s phaser s and trace back to their source . Captain Kirk orders that Ensign Chekov plot a course for the " Enterprise " to proceed to the source of the missiles at warp factor 3 . Meanwhile , during a routine health check , it is discovered that Dr . McCoy has a rare terminal illness , xenopolycythemia , which has no known cure and from which he will die within a year . McCoy insists that he can remain in his post on the " Enterprise " , but Kirk immediately informs Starfleet and requests a replacement . Act One . Arriving at the missiles ' point of origin , the " Enterprise " finds only what appears to be an asteroid , 200 miles in diameter , that is not in any orbit but follows an independent course through the local star system . Upon scanning , it is found that the " asteroid " is an atomic - powered spaceship . There are no living creatures detected , leading Spock to presume that the passengers are dead . More seriously , the asteroid ' s course , 241 - mark - 17 , puts it on a course to collide with the planet Daran V , a planet with a population of 3 . 724 billion , in 396 days . The " Enterprise " charts a parallel course to the asteroid / spaceship . Entering the transporter room , Kirk and Spock prepare to beam onto the asteroid / spaceship , but McCoy insists on joining them . Arriving inside the asteroid , they find a surface that appears geologically active , with a reddish sky , and are puzzled that the builders apparently wanted the inside of the ship to look just like the surface of a planet . The surface is dotted by large orange cylinders , from which a band of primitive , sword - bearing men emerges , led by a beautiful woman . After a brief melee , Kirk , Spock , and McCoy are captured , McCoy sharing a meaningful look with the woman before he is knocked unconscious . The beautiful woman introduces herself as Natira , the high priestess and leader of her people . Natira " welcomes " the officers to their world " Yonada " . The three are taken below the surface , where they encounter a large population of young and apparently healthy people . Natira leads the three into an Oracle Room , where she consults an unseen authoritative entity manifested by a decorative altar and a booming voice . Kirk and McCoy estimate that after 10 , 000 years in this multi - generational ship , the people no longer realize they are inside a spaceship . The Oracle " punishes " Kirk , Spock and McCoy by shocking them with an energy beam , rendering them unconscious . Act Two . The three regain consciousness , although McCoy remains out longer due to his illness , in some sort of guest area . Kirk then informs Spock about McCoy ' s condition . An old man enters the room and gives them a herb derivative to counteract the effects of the Oracle ' s attack , noting that many people on the ship have been punished in this way . When they tell him they are not from " Yonada " , he recalls how he once climbed the mountains , " even though it is forbidden , " and found that the world of " Yonada " is not a planet at all . " " For the world is hollow and I have touched the sky . . . " " , he says before collapsing to the ground . He dies immediately , apparently from a subcutaneous control device in his temple . Natira comes in , has the old man ' s body gently taken away , and seems to take a special interest in McCoy . Kirk recommends that McCoy use this to their advantage so that they may learn more about the civilization . The captain is faced with a triple dilemma : either risk violating the Prime Directive by informing the people of " Yonada " of their situation , destroy the asteroid with them in it or allow it to destroy Daran V . Natira admits she is in love with McCoy and wants him to stay on " Yonada " as her mate . She speaks of a final destination that is rich and green and notes that the Oracle has promised they shall reach it " soon . " When McCoy tells her he has only a year to live , she tells him even a day , a month , or a year with him will make her happy . Spock and Kirk make their way to the Oracle Room , and Spock recognizes the writing as that of the Fabrini , a civilization wiped out 10 , 000 years ago , when their star went nova . He also sees a symbolic map of the Fabrina solar system . Prior to dying out , the Fabrini had lived underground to protect themselves . They had also built this spaceship " Yonada " and programmed the Oracle of the People , which is actually a powerful computer , to take their surviving civilization to another habitable planet . The people of Yonada are their descendants . Spock manages to open the door , and the two conceal themselves in the temple behind a monolith as Natira enters . She asks the Oracle for permission to marry McCoy . The Oracle grants it , so long as McCoy agrees to join the Fabrini and submit to the instrument of obedience to become one of their people . As she ' s leaving , however , the Oracle discovers Kirk and Spock and zaps them . They are arrested and sentenced to death . Act Three . McCoy agrees to stay on " Yonada " but begs that Kirk and Spock be released . McCoy tells her he could never be happy on " Yonada " knowing that his two friends had died for his happiness . Natira agrees . As Kirk and Spock prepare to return , McCoy insists on staying . Kirk and McCoy briefly argue about his decision but Kirk agrees to leave him behind . He and Spock return to the " Enterprise " . In a ritual with the Oracle , McCoy has the instrument of obedience implanted in his head and he and Natira are married . At the Oracle ' s command , she reveals to him an ancient book that is to be opened and read when the ship reaches the " New World of the Promise . " Meanwhile , Kirk consults with Admiral Westervliet on a monitor in his quarters , who relieves him of all responsibility for the " Yonada " , saying that Starfleet Command will handle the situation . McCoy calls the ship with his communicator and tries to explain that by consulting the book Spock can change the " Yonada " s course . His instrument of obedience immediately sends him a shock of pain . He passes out as Natira enters . Act Four . Kirk and Spock beam back to the " Yonada " and Spock removes McCoy ' s instrument of obedience , shocking Natira . She tries to call for the guards , but Kirk subdues her and persuades her to give them a chance . He explains the history of the Fabrini and " Yonada " . She is very skeptical of the story and the Oracle begins to torment her through her instrument . She flees , but does not turn Kirk and Spock over to the guards . Kirk and Spock have found that a faulty part of the Oracle computer has caused a change in course . Natira consults the Oracle , which knocks her out . When Kirk , Spock , and McCoy arrive , she says she believes them and McCoy removes her instrument . Kirk and Spock move to take the book out of the temple , but the Oracle fights them , kicking up a storm and increasing the temperature in the room to 120 degrees planning to burn them to death or until they die of heat stroke . McCoy shows them how to open the pylon containing the book and Spock uses the book to disable the heating element , as well as the Oracle , and reprogram the spaceship ' s course . McCoy and Natira share a tearful farewell : She must stay to lead her people to the promised land and McCoy is determined to keep traveling the universe in search of a cure for his disease as well as for others afflicted . After correcting the " Yonada " s course , Spock shows Kirk the cylinders containing the vast database of the Fabrini , which contains medical knowledge , including the cure for xenopolycythemia . McCoy undergoes the very painful treatment for his illness , with Nurse Chapel at his side in the " Enterprise " s sickbay . Emerging cured , Kirk promises him the " Enterprise " will soon return to the area in 390 days when the " Yonada " eventually reaches its correct destination . McCoy is pleased by Kirk ' s promise and the " Enterprise " leaves " Yonada " . Memorable quotes . " " A lot can happen in a year . Please , give yourself every minute . " " " " Welcome to the world of Yonada . " " " " I can ' t say I think much of your welcome . " " " " We ' ve come in friendship . " " " " Then learn what it means to be our enemy before you learn what it means to be our friend . " " " " But things are not as they teach us . For the world is hollow , and I have touched the sky . " " " " Forgive him for he was an old man , and old men are sometimes foolish . " " " " But we ' re strangers to each other . " " " " But is not that the nature of men and women ? That the pleasure is in the learning of each other ? " " " " Until I saw you , there was nothing in my heart . It sustained my life , but nothing more . Now it sings . I could be happy to have that feeling for a day , a week , a month , a year . " " " " Kirk and Spock have committed sacrilege . You " know " what must be done . " " " " Is truth not truth for all ? " " " " Captain , informing these people they are on a ship may be a violation of the prime directive of Starfleet Command . " " " " Well the people of Yonada may be changed by the knowledge , but it ' s better than exterminating them . " " " " Logical , Captain . " " Links and references . References . asteroid ; atomic power ; " Bones " ; " Book of the People " ; Daran V ; electrical shock ; Fabrina ; Creators ; day ; Fabrini homeworld ; Fabrina solar system ; Fabrini ; fuel ; heating element ; hemoglobin ; instrument of obedience ; high priestess ; logic ; mile ; missile ; month ' nurse ; Oracle of the People ; oxygen ; parallel course ; physical examination ; Prime Directive ; red alert ; repent ; sacrilege ; sin ; spaceship ; star system ; Starfleet Command ; vow of obedience ; week ; xenopolycythemia ; year ; " Yonada "