Imagination

One's imagination referred to their ability to produce ideas in their mind.

Imagination was a relative dimension, (PROSE: Cat's Cradle: Time's Crucible, AUDIO: Auld Mortality) being involved in accessing the astral plane. (PROSE: Downtime) The Doctor of one universe believed his people had barely explored Imagination, and used the Possibility engine to access the dimension of Imagination alongside Possibility theory. (AUDIO: Auld Mortality) Imagination was related to memory, and Time's music was played on an instrument of imagination. (PROSE: Cat's Cradle: Time's Crucible)

Psychic paper worked based off the imagination of the person it was shown to. (TV: Flatline) When the Tenth Doctor showed his to Anya Kingdom and Mark Seven, he noted that the former had a bizarre imagination when she read it as "Grand High Prince of Skaro" and noted that the latter's could use some work when the android read it as "the Doctor". (AUDIO: The House of Kingdom) When Clara Oswald used to it pass herself off as a health and safety official, Fenton saw the paper as blank, something the Twelfth Doctor credited to the man's highly unimaginative mind. (TV: Flatline)

Charles Dickens wondered if his imagination had gone stale. (TV: The Unquiet Dead)

A technician told a UNIT officer not to let her imagination run away with her. (TV: Spearhead from Space)

The Krillitanes needed children rather than adults to unlock the Skasis Paradigm because of their imagination. (TV: School Reunion)

When the Fifth Doctor heard the White Guardian in his TARDIS, he wondered if it was just his imagination. (TV: Enlightenment)

A planet was destroyed when the imagination of the Doctor's TARDIS overloaded the Ch'otterai. (PROSE: The Mystery of the Haunted Cottage)

Sperantium was the chemical that fuelled imagination. It was harvested by Ronan Sumners, who used it to power New Port City's teleportation system. (PROSE: Gatecrashers)

Historians who had been allowed access to the "Monster Vaults" of the databanks in the Doctor's TARDIS identified that Abzorbaloff "for want of a better name" was a name given to the creatures who were not imaginative enough to come up with a name for themselves. (PROSE: The Monster Vault) By another account, an Abzorbaloff identified his son as an Abzorbalovian. (WC: The Genuine Article)

After the Daleks had reintroduced organic matter into themselves during the Dalek-Movellan War, they managed to tap into some residual imagination and make small gains in the war. This however revealed their nature as organic lifeforms to the Movellans who created a virus to target the Dalek mutant. (PROSE: Dalek: The Astounding Untold History of the Greatest Enemies of the Universe) During the Last Great Time War, the Dalek Empire created groups such as the Cult of Skaro, Eternity Circle and the Volatix Cabal to match the imagination of their Time Lord foes. (PROSE: A Brief History of Time Lords) Both the Tenth Doctor and Dalek Sec would later describe the Cult's function as "to imagine" either new ways of killing or survival. (TV: Doomsday, Daleks in Manhattan)