It is not until we come far down into the full daylight of history that we find men setting out with the conscious purpose of exploring the unknown for its own sake. With those early hunters it was doubtless new ground and new game that drew them on, but they too were attracted, consciously or unconsciously, by the spirit of adventure and the unknown--so deep in the soul of man does this divine force lie, the mainspring, perhaps, of the greatest of our actions. In every part of the world and in every age it has driven men forward on the path of evolution, and as long as the human ear can hear the breaking of waves over deep sea, so long will the fascination of the unknown carry the human mind forward and upward.

—Fridtjof Nansen