Thought

Thought was the process of the mind thinking, or having an idea. The primate cortex was the segment of the brain responsible for thought. (PROSE: Time and the Rani)

Thought travelled at the speed of light. (PROSE: The Sands of Time) The Vardans could travel along any form of broadcast wavelength, including thought. (TV: The Invasion of Time) Light was able to travel at the speed of thought. (TV: Ghost Light)