A book should contain pure discoveries, glimpses of terra firma, though by shipwrecked mariners, and not the art of navigation by those who have never been out of sight of land. They must not yield wheat and potatoes, but must themselves be the unconstrained and natural harvest of their author's lives.
Henry David Thoreau (1817–1862), U.S. philosopher, author, naturalist. A Week on the Concord and Merrimack Rivers (1849), in The Writings of Henry David Thoreau, vol. 1, p. 100, Houghton Mifflin (1906).