peaks, but we knew nothing of the exact nature and history of the mountain forms. No one had up to that time given us a picture of the mountain landscapes in modern terms; that is, in terms that conveyed exact impressions and in contrast to the vague, general terms such as the casual traveler may employ in painting a picture that makes a special appeal to him.
The Five Main Fields of Exploration
The desert has furnished one of the five main fields of explor- ation in historical times, the other four being the polar regions, the unknown mountains of the world, the tropical forests, and the islands of the sea. Mountains were once objects of venera- tion and awe and even of worship. Many peoples considered them the abode of evil spirits. Their dark defiles, their great uninhabited spaces, their wild storms, all of which have excited the imagination and attracted the explorer in modern times, were fearsome things to the plains dweller who knew the mountains only by reputation or by legends that came down to lowland cities from mountain folk or from passing travelers. Where the modern man goes voyaging for adventure and pleas- ure among distant and little-known islands in remote parts of the sea, there the European at the dawn of civilization saw only outer darkness or the abode of strange peoples and listened to legends of islands that were said to have vanished beneath the ocean. Equally strange as distant islands, equally fearsome as the mountains, were the vast inner recesses of the tropical forests when their margins first became known to the explorer and the settler. The sources of the great rivers that flowed through them were in most cases unknown, and quite unknown at first were the peoples who lived on their banks or in clearings in the forest. For a long time it was believed that the Amazon forest was the home of the strange folk that legend had pic- tured, and one expedition after the other went out to find them. The extraordinary animal and human life of the central African forest long furnished one of the greatest incentives to explora- tion, an incentive that draws men even today. The conquest of the poles of the earth, like the conquest of high mountain
