We have the power to do anything we like. Absolute power over every particle in the universe. Everything that has ever existed or ever will exist, as from this moment. Are you listening to me, Romana? Because if you're not listening, I can make you listen. Because I can do anything. As from this moment there is no such thing as free will in the entire universe — there is only my will, because I possess the Key to Time.
— The Doctor, in “The Armageddon Factor”