Starting with a definite illustration before us of a sailing boat of about 8000 years ago, our mind naturally wanders back to the period when the first boat was ever made. Picture, if you will, the prehistoric man standing by the banks of the Tigris or Euphrates gazing in utter helplessness and awe at the liquid mass gurgling on its way to the Persian Gulf. He sees the fishes able to swim beneath its surface and the waterfowl to float above. Then when his mind has reached a sufficiently developed state to permit of his being able to reason, he begins to wonder if he—the superior to fish and fowl—could also be supported in the water until he has reached the other side of the river on which he has as yet never set foot. So, on a day, greatly daring, he entrusts his body to the flowing stream, and at length discovers that by certain exercises he is able to float and swim across to the other side. A new accomplishment has been made, a new world has been opened out to him. When he gets back home he begins to reason still further. How can he carry himself, his family, his goods to the other side? One day, perhaps, while hewing down a tree for his hut, a branch falls into the water. Behold! it possesses the ability of the water-fowl—it floats. So he hews down the trunk itself, sits across it, and for sport, launches off from the bank. Lo! the trunk supports both its own weight and his. Thus encouraged, his primitive mind sets slowly to work. “If I get a bigger trunk and hollow it out, it will carry me, my family and my property across to the other shore.” So having turned the trunk into a boat, he makes of the branch a punting-pole. At a later stage he puts on a cross-piece to one end of the pole and thus propels himself by paddling, until this in turn becomes an oar. Since human nature differs but little from age to age, and its chief tendency is ever to proceed along the route of least resistance, he begins to seek some means of motion without work. His descendants improve upon the tree-trunk until it has become more shapely and less clumsy. Then while returning home one evening, tired out with paddling and hunting, he rests on his paddle for a moment! Yet still his boat moves. He holds up the blade of his paddle and the canoe moves a little faster. He stands up, and, the larger the space that is exposed to the wind blowing in the direction in which he is travelling, the more quickly still does the little ship run on. Next day he brings with him a stick which he erects in the boat. That will save him standing. To the stick he makes fast a hide and spreading it to the wind sails faster than anything he has ever seen float on the water.