How Sharper Than a Serpent ' s Tooth ( episode ) The " Enterprise " encounters a being that once visited the ancient peoples of Earth . Summary . Soon , the " Enterprise " encounters an alien vessel that is approaching on the same course as the probe . It is twice the size of the " Enterprise " , surrounded by an immense energy field and composed of crystalline ceramic . A globular force field encompasses the Federation vessel . The alien ship probes the " Enterprise " , then the surrounding energy pattern shifts and transforms itself into the shape of a large feathered serpent , which Ensign Walking Bear , an " Enterprise " helmsman , recognizes as Kukulkan . Upset over being forgotten by Earthlings , Kukulkan gives the crew one chance to redeem themselves because one crewman did not forget him . Kukulkan states that if they fail him again , all of their kind shall perish . When asked , Walking Bear tells Captain Kirk that he is a Comanche and has studied his background . The ship bears a strong resemblance to a god of ancient Mayan and Aztec legends . The Mayans had a legend of a winged serpent god who came from the skies . They could conceivably be dealing with a space traveler who visited Earth in early times and was the basis for such legends . As Kirk ponders why Kukulkan would want to destroy them , McCoy disappears from sickbay and Scott vanishes from engineering . On the bridge , as Kirk asks Walking Bear more about the ancient legends of Kukulkan , the helmsman too disappears . After that , Kirk vanishes as well , leaving Spock in command of the " Enterprise " . Inside the other ship , Kirk asks Walking Bear if legend says what happened to Kukulkan . The ensign tells him no , only that he left and promised to return one day . Kirk surmises that the space probe was his . Kukulkan says , " " Now I have shown you the seeds I have sown before . Learn from them . Find their purpose if you can . Only then will I appear before you . " " If they fail , the crew of the " Enterprise " will all perish . The four crew members are transported to an Earth - like city filled with many cultures that appears to be one gigantic riddle , as Kirk points out . Walking Bear tells Kirk that Kulkukan gave the Mayans a remarkably accurate calendar and instructed them to build a city according to its cycles . When the city was finished , Kukulkan was supposed to return . The Mayans built their city and waited . Kukulkan never appeared . Kirk reasons that he must have visited several ancient people on Earth but each one only used part of his knowledge to build their cultures . If no one built this city exactly right , that is why Kukulkan never came back . The city is the key . It must contain some sort of signaling device . Kirk decides that it must be the pyramid in the center of the city that may be the key to figuring out the riddle . He climbs it and gets McCoy , Scott , and Walking Bear to turn the heads of the serpent statues to all strike a certain space on the pyramid . When they accomplish the task , Kukulkan appears as the winged serpent , alleging to be their master . He claims they strayed from the path he set . Kirk claims he doesn ' t know him so Kukulkan will teach him . Transported to an ominous " life - room , " the crew members notice a variety of creatures from around the galaxy , all in small cages . There is even a ferocious , but now peaceful , Capellan power - cat . Kukulkan says they are contented . Each creature ' s mind thinks that it is on its own world , created by Kukulkan ' s machinery . They are his only companions , his children to be shown how to live . Kirk says , " " If children are made totally dependent on their teachers , they will never be anything but children . " " Kukulkan has had enough . Despite what he has shown them , they still cling to their disobedient ways . Kirk explains that they cannot accept Kukulkan as their master , despite his contributions to mankind . On the " Enterprise " , Spock discovers a way to break the energy field surrounding the ship , distracting Kukulkan from the other crewmen . Kirk and McCoy remove a large tube connected to the Capellan power - cat ' s cage which keeps its mind at rest . The cat awakens and this causes it to break out of its cage with its naturally produced electricity . The power - cat barges around the room and causes the other animals to be released from their cages , thereby creating a chaos which Kukulkan is unable to control . The power - cat traps Kukulkan , which forces him to reveal himself as a mortal . Kirk saves Kukulkan and thus teaches him a valuable lesson about Human survival . Kukulkan leaves as an old , broken mortal , and Kirk decides that the price of infinite knowledge is too high to pay . McCoy reminds them of a line from Shakespeare ' s " King Lear " , " " How sharper than a serpent ' s tooth it is to have a thankless child . " " Memorable quotes . " " You will be given one chance to succeed where your ancestors failed . Fail me again and all of your kind shall perish ! " " " " You don ' t deserve it yeoman , but you ' re getting a few days bed rest . " " " " This city is one gigantic riddle . " " " " Intelligent life is too precious a thing to be led by the nose . " " " " Vulcan was visited by alien beings . They left much wiser . " " " " Just once , I wish he ' d let us use the stairs . " " Links and references . References . Aztec ; " Bones " ; calendar ; Capellan power - cat ; central power source ; Chinese dragon ; clay ; Comanche ; crystalline ceramic ; disrupted matter ; dragon ; Earth ; Earth ' s system ; Egypt ; energy field ; energy amplification system ; evasive action ; Federation ; flexibility ; globular force field ( force globe ) ; God ; homeworld ; hypo ; Human history ; jungle ; " King Lear " ; kitten ; Kukulkan ' s city ; Kukulkan ' s machinery ; Kukulkan ' s probe ; Kukulkan ' s species ; Kukulkan ' s starship ; Kukulkan ' s zoo ; library computer ; light year ; Mayan ( Mayas ) ; medical kit ; Native American ; obelisk ; pyramid ; Quetzalcoatl ; serpent ; ; signaling device ; standard greeting ; Starbase 21 ; Starfleet ; spiral evasive course ; Toltec ; tranquilizer ; volt ; Vulcan s ; Vulcan ( planet ) ; warp catapult effect ; yellow alert ; yeoman ; zoo