Madness and Intelligence
Men have called me mad; but the question is not settled whether madness is or is not the loftiest intelligence - whether much that is glorious - whether all that is profound - does not spring from disease of thought - from moods of mind exalted at the expense of the general intellect. They who dream by day are cognizant of many things which escape those who only dream by night. In their gray visions they obtain glimpses of eternity, and thrill, in waking, to find that they have been upon the verge of the great secret. In snatches, they learn something of the wisdom which is of good, and more of the mere knowledge which is of evil. They penetrate, however rudderless or compassless, into the vast ocean of the ‘light ineffable’
Edgar Allan Poe, in 'Eleonora'