"The discoveries in Isle Royale throw a new light on the character of the 'Mound Builders,' giving us a totally distinct conception of them, and dignifying them with something of the prowess and spirit of adventure which we associate with the higher races. The copper, the result of their mining, to be available, must, in all probability, have been conveyed in vessels, great or small, across a treacherous and stormy sea, whose dangers are formidable to us now, being dreaded even by our largest craft, and often proving their destruction. Leaving their homes, those men dared to face the unknown, to brave the hardships and perils of the deep and of the wilderness, actuated by an ambition which we to-day would not be ashamed to acknowledge." Such vast works in so remote a land must have been inspired by the commercial necessities of some great civilization; and why not by that ancient and mighty people who covered Europe, Asia, and Africa with their manufactures of bronze--and who possessed, as Plato tells us, enormous fleets trading to all parts of the inhabited world--whose cities roared with the continual tumult of traffic, whose dominion extended to Italy and Egypt, and who held parts of "the great opposite continent" of America under their control? A continuous water-way led, from the island of Atlantis to the Gulf of Mexico, and thence up the Mississippi River and its tributaries almost to these very mines of Lake Superior. Arthur Mitchell says ("The Past in the Present," p. 132),