Unlike the Concord, the Merrimack is not a dead but a living stream, though it has less life within its waters and on its banks. It has a swift current, and, in this part of its course, a clayey bottom, almost no weeds, and comparatively few fishes.
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. 90, Houghton Mifflin (1906).