We are now ready to start on our way down the Great Unknown. Our boats...are chafing each other, as they are tossed by the fretful river. We have but a months rations remaining. The flour has been resisted through the mosquito-net sieve; the spoiled bacon has been dried...the sugar has all melted and gone on its way down the river. We are three quarters of a mile in the depths of the earth, and the great river shrinks into insignificance, as it dashes its angry waves agains the walls and cliffs, that rise to the world above; they are but puny ripples, and we are but pygmies, running up and down the sands, or lost among the boulders. 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 know not; what walls rise over the river, we know not.

-John Wesley Powell