The Fourth Doctor once explained the principle to Leela by using the analogy of how a larger cube might appear to be able to fit inside a smaller one were the larger cube further away, yet immediately accessible at the same time. He described this as "a key Time Lord discovery". (TV: The Robots of Death) Rory Williams later surprised the Eleventh Doctor with his understanding of the principle, that the inside was "another dimension". (TV: The Vampires of Venice) The Daleks were capable of creating dimensionally transcendent factory ships. (PROSE: War of the Daleks)