Down the Great Unknown: John Wesley Powell's 1869 Journey of Discovery and Tragedy Through the Grand Canyon 1st edition by Dolnick, Edward (2001) Hardcover

Quote from John Wesley Powell at start of the book: “We are now ready to start on our way down the Great Unknown…We are three quarters of a mile in the depths of the earth …We have an unknown distance yet to run; an unknown river yet to explore. What falls there are, we know not; what rocks beset the channel, we known not; what walls rise over the river, we know not. Ah, well! We may conjecture many things. The men talk as cheerfully as ever; jests are bandied about freely this morning; but to me the cheer is somber and the jests are ghastly.