For the World Is Hollow and I Have Touched the Sky

Plot

Dr. McCoy, the Federation starship USS Enterprise's Chief Medical Officer, discovers he has a rare, incurable disease called xenopolycythemia (as in polycythemia) and has only one year to live.

The Enterprise is targeted by ballistic missiles, but they easily destroy the primitive weapons, tracing their point of origin to a large asteroid called Yonada. They find Yonada is on course to collide with the heavily-populated planet Daran V within a solar year, which would be catastrophic. They scan the asteroid and find it has a breathable internal atmosphere. Captain Kirk, First Officer Spock, and Dr. McCoy transport over to investigate. They discover that Yonada is populated by a highly religious society of humanoids that worship their Oracle. The High Priestess, Natira, orders the capture of the three and takes them to the Oracle. Kirk attempts to explain that they have come in peace but the Oracle knocks them unconscious with an electric shock.

When they wake, an old man approaches them, having heard of their arrival, and tells them that he has seen the outside of the asteroid, stating "...for the world is hollow and I have touched the sky". Suddenly he goes into shock and dies, and McCoy discovers a glowing device under the man's temple. They learn that all on Yonada have been implanted with such "instruments of obedience" under the Oracle's control. Reminding them again of the punishment for disobedience, Natira allows the three to explore the asteroid. McCoy stays with Natira, as the two are beginning to develop a relationship, while Kirk and Spock discover the asteroid is really a generation ship housing millions of beings of the Fabrini race. The ship was launched over 10,000 years prior to escape the destruction of their world by a supernova but the current residents are unaware of the nature of their world. Kirk and Spock, having secretly re-entered the Oracle room, watch as Natira privately prays to it about marrying McCoy. The Oracle agrees if he will accept an obedience device. It then viciously shocks Kirk and Spock again. Natira says she must execute them for their transgression but McCoy persuades her to relent. As Kirk and Spock prepare to beam back to the Enterprise McCoy insists on staying behind with Natira even if Starfleet has to destroy the generation ship to protect Daran V.

McCoy accepts an Instrument of Obedience and marries Natira, who shows him their sacred text, the "Book of the People". McCoy learns it contains a large amount of information on Fabrini technology and other star systems and calls the Enterprise to share this information. The Oracle detects McCoy's communication and activates his obedience device. Kirk and Spock transport back to Yonada to find him unconscious. Spock removes the device from McCoy while Kirk tries to explain the truth to Natira. Natira starts to believe Kirk but the Oracle actives her device and nearly kills her. Having recovered, McCoy removes her device while Kirk and Spock again seek the Oracle, convinced it is an automated system. Spock learns from the Book how to enter the control room behind the Oracle where they discover the ship's navigational controls. They correct Yonada's course to avoid colliding with Daran V. Spock discovers the Fabrini archives, which contain a cure for McCoy's condition among other medical advances. McCoy returns to the Enterprise where he is successfully treated, hoping to return to see Natira again when Yonada arrives at its new homeworld in just another year.

Reception

Zack Handlen of The A.V. Club gave the episode an 'B-' rating, describing it as having potential, but being hampered by a script that fails to act on that: "we have Kirk and Spock unraveling the mystery by the halfway mark, and then spending the rest of the episode on clean-up duty. You know McCoy is coming back, you know he'll be cured, and you know that the computer will be defeated. About the only question is whether or not Natira will make it to the end credits, and happily, she does—which means McCoy, unlike Kirk, isn't a widower."

Star Trek novelist Dayton Ward wrote,

"For the World is Hollow and I Have Touched the Sky" is a decent idea, in and of itself. The idea of a generational ship encased in an asteroid is well worth exploring. After all, variations on the concept were already a staple of science fiction long before Star Trek came along. My biggest problem is why someone—the Fabrini—felt it necessary to conceal the truth behind the "worldship" from its population. Wouldn't it make more sense for the generations of Yonadans to be informed as to their purpose, and be working and training the next generation(s) to be ready for when the ship arrives at its destination? Instead, they're wandering the halls, apparently doing little more than tossing Frisbees and getting the occasional spanking from the Oracle. ... The episode is typical of the third season: Long on talk, light on action, adequate yet hardly spectacular in execution.

David Alan Mack, also a Star Trek novelist, remarks on the episode's

peculiar similarity to "The Paradise Syndrome", which aired only five weeks prior. Both episodes involve the Enterprise being tasked with altering the trajectory of an asteroid headed toward a populated Class M planet, discovering a displaced culture with a love of peculiar obelisks, and one of our series regulars getting married to the culture's high priestess. In fact, these episodes are so similar that they reused the effects shot of the asteroid from The Paradise Syndrome as a stand-in for the asteroid-disguised generation ship Yonada.

Mack writes that he "simply didn't buy the romance between McCoy and Natira," but otherwise liked the characterizations:

The episode's performances are quite good, all things considered. William Shatner's scenery chewing is kept in check, and DeForest Kelley brings a quiet dignity to his portrayal of McCoy facing his own imminent demise. The argument between McCoy and Nurse Christine Chapel (Majel Barrett) feels genuine and heartfelt, and Leonard Nimoy brings the perfect degree of quiet compassion to the moment when Spock, having learned of McCoy's illness, reaches out to steady his wounded friend, and McCoy reacts with understated surprise at Spock's sudden display of concern. In fact, that scene is the best one in the entire episode, because it captures the dynamics of the three principals' friendship in a single, eloquently dramatized moment.

Samuel Walters called it "a surprisingly effective episode about blind faith in rules and dogma, as well as a touching love story," with the qualification that the story "does a good job of providing character growth for McCoy. Had the episode not succumbed to an easy solution to his predicament—purely because these episodes need their characters to remain, essentially, the same—then this could have been a profound, moving narrative." A negative review by Michelle Erica Green focused on plot illogic: "Why are the men wearing shiny plaid suits and carrying swords when wrongdoers can be punished for their crimes by a computer? Why are the women wearing provocative gowns when only the priestess is allowed to choose her own mate?"

Game creator Jon Van Caneghem used the plot of this as the basis for his first computer game, Might and Magic Book One: The Secret of the Inner Sanctum.