No man will be found in whose mind airy notions do not sometimes tyrannise, and force him to hope or fear beyond the limits of sober probability.
 Samuel Johnson, The History of Rasselas, Prince of Abissinia (1759). copy citation

Context

“Perhaps if we speak with rigorous exactness, no human mind is in its right state. There is no man whose imagination does not sometimes predominate over his reason who can regulate his attention wholly by his will, and whose ideas will come and go at his command. No man will be found in whose mind airy notions do not sometimes tyrannise, and force him to hope or fear beyond the limits of sober probability. All power of fancy over reason is a degree of insanity, but while this power is such as we can control and repress it is not visible to others, nor considered as any deprivation of the mental faculties;” source