"Robinson Crusoe, as is well known, built his house, from motives of health, on the south side of the mountain, whereas his crops grew on the damp but fruitful northern slopes. He was therefore obliged to carry his harvests over the mountain. To eliminate this labour he decided to construct a canal around the mountain. The time required for this enterprise which, to avoid silting, would have to be continued without interruption, he estimated at three years. He had therefore to lay in provisions for three years." (Gesell, A Story of Robinson Crusoe)