Key to Time The Key to Time was a powerful and legendary artefact which the Guardians of Time used to maintain the equilibrium of time itself , ( TV : " The Ribos Operation " ) controlling omniversal order and chaos . It was a perfect crystalline cube split into six pieces , with each of the Guardians responsible for a piece , as it would be the end of time without the Key . ( AUDIO : " The Judgement of Isskar " ) Nature and functions . Existing at every point in time , ( PROSE : " The Well - Mannered War " ) its shape was that of a perfect transdimensional crystalline cube , an orderly pattern extending through four dimension s , comprised of six segments pieced together to gain the full power of the Key . Temporary segments could be created if one had enough components of the original Key to access at least some of its power , but this was dangerous as the Key ' s segments were linked on a fundamental level . Cessair of Diplos had found out how to use the segment she had obtained to travel to Earth , and use its power of transmogrification , temporarily appearing as the Fourth Doctor to Romana . ( TV : " The Stones of Blood " ) Romana warned the Doctor that transforming another piece back to its four dimensional crystalline form would suck an incoming Cronquist invasion force to Earth " in the twinkling of an eye " . ( AUDIO : " Ferril ' s Folly " ) Another fragment gave its holder the ability to see the future , and demonstrated enough power to make a normal - sized squid grow to gigantic proportions after swallowing it . ( TV : " The Power of Kroll " ) The individual segments were very tough and resistant to damage ; The Tara n Lamia blunted two of her diamond drills experimenting on one of them . ( TV : " The Androids of Tara " ) They could be transformed back into their original form by the Core to the Key to Time , or dispersed by it , reforming somewhere else in another form . ( AUDIO : " Ferril ' s Folly " ) Alternatively , the segments could be turned back into their disguised forms . ( AUDIO : " The Chaos Pool " ) The Key didn ' t affect its operators , in order to let them use it . ( TV : " The Armageddon Factor " ) It was said to maintain balance and equilibrium , similarly to the Eye of Harmony - with the result that disrupting the links between the segments could damage the fabric of the universe . It could rewrite matter , change the state of quanta and start and stop the universe . ( AUDIO : " The Judgement of Isskar " ) The sixth segment in particular was supposedly the most powerful of the segments ( AUDIO : " Luna Romana " ) and repeatedly took on an organic configuration when disguised . ( TV : " The Armageddon Factor " , AUDIO : " The Chaos Pool " ) Reconfiguring the sixth segment into its original form before doing so to the fifth segment would cause a temporal quake that could rip apart the space - time continuum . ( AUDIO : " The Destroyer of Delights " ) At some stage , the Master obtained a segment of the Key to Time and used it to tear apart the constellation of Mandusus . ( PROSE : " Cold Fusion " ) The Crimson Hand later had a segment of one of the Keys to Time . ( COMIC : " The Crimson Hand " ) History . Creation . The Key to Time was originally created by the Grace — powerful beings from outside time who used the Guardians of Time as their agents , ( AUDIO : " The Judgement of Isskar " ) though the Guardians claimed to have forged the Key , and the Jewel , from primal materials . In the distant past , the Council of Guardians used the Key to wipe the memories of the participants in the Millennium War , and later used it to spin from the same primal materials the crystal prison within which they trapped Kronos . ( PROSE : " The Quantum Archangel " ) The Doctor ' s first quest for the segments . On at least four occasions , the Doctor was sent on quests to assemble the key from its secretly scattered and disguised fragments . The quest . Needing the key to maintain universal balance , the White Guardian enlisted the Fourth Doctor to gather the Key ' s six segments , which were hidden in the forms of objects & icons of power . To help him , he enlisted the help of the Time Lord Romana , to whom the White Guardian had misleadingly appeared as the Lord President of Gallifrey . Romana , whom the White Guardian had entrusted with a tracer , would serve as the Doctor ' s companion during the quest . ( TV : " The Ribos Operation " ) Although generally focused on his quest for the Key to Time , the Doctor could become distracted and diverted , both by local events and disruptions to the Tracer . On one occasion , the TARDIS was diverted to the planet Ashkellia when a breach in the higher dimensions disrupted the Tracer ( PROSE : " Tomb of Valdemar " ) , and after a visit to Earth ( TV : " The Stones of Blood " ) , the abundance of chronon radiation caused by the Dragon Paths forced the Doctor and Romana to remain on Earth to deal with the source of the radiation , as otherwise the Tracer would be unable to lock onto the next segment ( PROSE : " The Shadow of Weng - Chiang " ) . On another occasion , the Doctor was simultaneously called upon by the Time Lords to investigate a rift in reality and drawn to Earth to find the kidnapped Brigadier Lethbridge - Stewart , although other such diversions took place during their search ( PROSE : " Heart of TARDIS " ) . During a confrontation with the Doctor ' s old foe Quadrigger Stoyn , Stoyn briefly stole the TARDIS and buried the fifth segment of the Key on a hill in Italy a year before the theft , allowing him to set a trap that would draw in the Doctor and Romana and allow him to steal the TARDIS in the first place ( AUDIO : " Luna Romana " ) . At this point , the Doctor revealed that he had actually been hesitant to reclaim the final portion of the Key as he feared what would happen to it . The Black Guardian used the Shadow in an attempt to stop the Doctor from obtaining the sixth segment . Once the Doctor had defeated the Shadow , he assembled the Key and outwitted the Black Guardian , enabling the White Guardian to restore universal balance . The Key was then broken apart and scattered throughout the universe again , assuming five new shapes and restoring Princess Astra to her natural form . The Black Guardian swore revenge on the Doctor , who went on the run from him . ( TV : " The Armageddon Factor " ) In an alternative timeline in which Romana never left Gallifrey , it was Leela and K9 Mark I who accompanied the Doctor on his search for the Key to Time . In this timeline , Leela was the only human to have held the Key in her hands . ( AUDIO : " Reborn " ) Search by the Doctor ' s fifth incarnation . The Fifth Doctor searched for the Key to Time on at least two separate occasions . On one occasion , he gathered three unspecified segments to escape the Labyrinth of Death . ( GAME : " The First Adventure " ) The Doctor was later sent on another quest for three of the six scattered segments by Amy , a Tracer in the form of a young human , due to his previous use of the Key with a substitute sixth segment . This upset the balance among the other segments , causing them to decay and disrupt time and space around their current locations . The Grace had meanwhile sent another Tracer , Zara , in search of the segments , intending for each Tracer to find three segments to prevent anyone gaining the full power of the Key . Things went wrong when Zara was corrupted and convinced to seek the power of the full Key for herself , while Amy became increasingly opposed to her original purpose as the Doctor helped her become a person . ( AUDIO : " The Judgement of Isskar " ) Zara joined forces with the White Guardian some time after this and eventually the Doctor and Amy . They gave the completed key to the Doctor , allowing him to destroy it in the Chaos Pool , where it had been created . This prevented the Black and White Guardians from using it and simultaneously scattering the Grace — who had personified in the Key — across all of Time , preventing any of them from using the Key as he recognised that its power was too great . ( AUDIO : " The Chaos Pool " ) Search by the Doctor ' s seventh incarnation . Years later , the White Guardian sent the Seventh Doctor , Ace and Benny on a quest to find the six segments of the Key to Time . They were scattered across the Doctor ' s personal past and disguised as items connected with him in some way . ( COMIC : " Time & Time Again " ) Behind the scenes . As part of a the " Watch Out " / " Out And About " segment while hosting , David Tennant pretended to auction off a Key to Time - which was the only one in existence and stolen from the victim by a friend who was in on the joke - at a " Doctor Who " auction . Once Tennant had revealed it was a joke , the victim of the joke exclaimed , " David Tennant , you ' re a bastard ! "