How do you suppose I know about all these things that took place so long ago? I don’t. I’m only guessing about them. But there are different kinds of guesses. If I hold out my two closed hands and ask you to guess which one has the penny in it, that is one kind of a guess. Your guess might be right or it might be wrong. It would be just luck. But there is another kind of a guess. When there is snow on the ground and I see tracks of a boot in the snow, I guess that a man must have passed by, for boots don’t usually walk without some one in them. That kind of a guess is not just luck but common sense. And so we can guess about a great many things that have taken place long ago, even though there was no one there at the time to see them or tell about them. Men have dug down deep under the ground in different parts of the world and have found there--what do you suppose? I don’t believe you would ever guess. They have found the heads of arrows and spears and hatchets. The peculiar thing about these arrows and spears and hatchets is that they are not made of iron or steel, as you might expect, but of stone. Now, we are sure that only men could have made and used such things, for birds and fish or other animals do not use hatchets or spears. We are also sure that these men must have lived long, long years ago before iron and steel were known, because it must have taken long, long years for these things to have become covered up so deep by dust and dirt. We have also found the bones of the people themselves, who must have died thousands upon thousands of years ago, long before any one began to write down history. So we know that the people who were living on the earth then were working and playing, eating and fighting--doing many of the same things we are to-day--especially the fighting. This time in the pre-history of the world, when people used such things made of stone, is therefore called THE STONE AGE. These First Stone Age People we call _Primitive_, which simply means First as a Primer means First Reader. Primitive People were wild animals. Unlike other wild animals, however, they walked on their hind legs. These First People had hair growing, not just on their heads, but all over their bodies, like some shaggy dogs. They had no houses of any sort in which to live. They simply lay down on the ground when night came. Later, when the earth became cold, they found caves in the rocks or in the hillsides where they could get away from the cold and storms and other wild animals. So men, women, and children of this time were called _Cave People_.