Ancient man was much afraid of: thunderstorms, lightning, storms, wild animals. He had feared and fire. Many years passed before our ancient ancestor realized that the fire can be not only the enemy, but also a friend. And realizing this, he wished to "tame" the fire, to force him to "serve" themselves. Often as a result of lightning lit the dry stump, and man, since taking the plunge, brought a few smouldering embers in your home. First, man has learned to support brought the fire. Then our ancient ancestor noticed that the friction generates heat. It was this discovery helped him to learn how to make fire by friction of wood on wood.
Next, the process of making fire was improved: the Romans, lighting the hearth, used a magnifying glass. Later they had to carve a spark from a flint, and then used the flint and tinder.
This method of fire-making (the friction of wood on wood) still exists in some African tribes.