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)

The Cult of Skaro was formed to imagine new ways for the Daleks to survive. (TV: Doomsday)

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)

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)