Every traveler has a different tale, but the travel itself has the same purpose: to push through boundaries, overcome obstacles, and to seek out what is not known. This impulse in man will never change. And it is right that this is so, for without it the progress of the human race might come to a shuddering halt. In reviewing the lives and careers of great travelers, we feel almost as if they were animated by some unconscious impulse, some unfathomable compulsion, to thrust out the boundaries of their knowledge. Every man must determine for himself his own outer limit. The demarcation is intense, and personal; and it cannot be any other way.