It should not be forgotten that De Soto, a Spanish explorer, had discovered the Mississippi at a point not far from the present city of Memphis, in the year 1541, a hundred and thirty-two years before the voyage of Joliet and Marquette; but the knowledge of that discovery had faded from men's minds. They actually passed over the spot where De Soto had crossed the river in the previous century, though apparently they were not aware of that fact, for no mention is made in Marquette's journal of De Soto or his discovery. The chief significance of the Chicago portage to the explorers when they passed it was the view of the lake which they had as they descended the stream towards its mouth. Lake Michigan, indeed, had been discovered long before, but it was known only along its northern shores extending as far as Green Bay, which had been entered by the missionaries, a station being established at its farthest extremity. The southern extension of Lake Michigan was unknown until Joliet and Marquette paddled into it with their canoes as they left the Chicago River. No date was mentioned by Marquette in his journal of the arrival of the party in the river, but it must have been about the beginning of September, 1673. Joliet also kept a journal, but unfortunately he lost all his papers in a canoe accident before he reached Quebec on his return. That the site of the future Chicago, situated as it was on so important a portage connecting the lake with the river systems of the interior, possessed advantages of a striking kind was plainly perceived by Joliet, who afterward wrote that an artificial waterway could easily be constructed by cutting only a half league of prairie, "to pass from the Lake of the Illinois into St. Louis River." Thus, upon reaching the mission station of St. Francis Xavier, situated near the mouth of the Fox River, from which they had started, the explorers had completed a journey of about twenty-five hundred miles in a period of four months, had opened to the eyes of the world the wonderful river of the West, had incidentally discovered the site of the future great city of Chicago, and had made the complete circuit back to Green Bay without the loss of a man or the occurrence of a single untoward accident.