The design of the expedition was no less than the discovery of the true source of the "Father of Waters," the mighty Mississippi; and a voyage thence, in a canoe, to its mouth in the Gulf of Mexico. It was a novel and daring project. The idea of such an undertaking had occurred to him while on his horseback journey across the continent; of which a brief outline has been given the reader in previous chapters. He had come to a point in his onward progress which is noted for its beauty, being one of the most picturesque spots on the Mississippi, the bridge spanning the river between Iowa and Illinois, where the rock-divided stream flows grandly by under the shadow of towering bluffs. His own words best describe the impression which the scene made upon him, and the consequent birth in his brain of the most notable achievement of his life:-- "While crossing the continent on horseback from ocean to ocean, in 1876, I came to a bridge which spans the Mississippi between Rock Island, Illinois, and Davenport, Iowa. As I saw the flood of this mighty stream rolling beneath me, I turned in imagination to its discovery in 1541. I saw the renowned De Soto upon its banks and buried in its depths: I accompanied Marquette from the mouth of the Wisconsin to the mouth of the Arkansas: I followed Father Hennepin northward to St. Anthony's Falls: and I saw the daring La Salle plant the banner of France on the shores of the Gulf of Mexico. "Musing thus upon the exploits of the heroic old explorers who led the way to this grand and peerless river of North America, I felt that it was a subject of much regret that although its mouth was discovered by the Chevalier La Salle nearly two hundred years ago, there was still much uncertainty as to its true source. Within the last century several distinguished explorers have attempted to find the primal reservoir of the Great River. Beltrami, Nicollett, and Schoolcraft have each in turn claimed the goal of their explorations. Numerous lakes, ponds, and rivers have from time to time enjoyed the honor of standing at the head of the 'Father of Waters.' Schoolcraft, finally, in 1832, decided upon a lake, which he named Itasca, as the fountain-head, and succeeded in securing for it the recognition of geographers and map-makers. "Notwithstanding the fact, however, that the claim for geographical honors was very generally accorded to Schoolcraft's lake, as being the source of the Mississippi, I had frequently been told that many Indians denied that their ideal river began its course in Lake Itasca, and asserted that there were other lakes and rivers above and beyond that lake, unknown to the white man, and that in them was to be found the original starting forth of the mysterious stream. These reflections led me to conclude that there was yet a rich field for exploration in the wilds of Minnesota."