Imagination

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)

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)