I recently read The List (New Haven: Yale University Press, 2004) by Robert E. Belknap. Mr. Belknap used this fine quote from Ralph Waldo Emerson (which a small amount of internet research reveals is drawn from Emerson’s Nature) as his epigraph:
“He will perceive that there are far more excellent qualities in the student than preciseness and infallibility; that a guess is often more fruitful than an indisputable affirmation, and that a dream may let us deeper into the secret of nature than a hundred concerted experiments.”