In this way thousands of years passed. Only the people with the cleverest brains survived. They had to struggle day and night against cold and hunger. They were forced to invent tools. They learned how to sharpen stones into axes and how to make hammers. They were obliged to put up large stores of food for the endless days of the winter and they found that clay could be made into bowls and jars and hardened in the rays of the sun. And so the glacial period, which had threatened to destroy the human race, became its greatest teacher because it forced man to use his brain. HIEROGLYPHICS THE EGYPTIANS INVENT THE ART OF WRITING AND THE RECORD OF HISTORY BEGINS THESE earliest ancestors of ours who lived in the great European wilderness were rapidly learning many new things. It is safe to say that in due course of time they would have given up the ways of savages and would have developed a civilisation of their own. But suddenly there came an end to their isolation. They were discovered. A traveller from an unknown southland who had dared to cross the sea and the high mountain passes had found his way to the wild people of the European continent. He came from Africa. His home was in Egypt. The valley of the Nile had developed a high stage of civilisation thousands of years before the people of the west had dreamed of the possibilities of a fork or a wheel or a house. And we shall therefore leave our great-great-grandfathers in their caves, while we visit the southern and eastern shores of the Mediterranean, where stood the earliest school of the human race. The Egyptians have taught us many things. They were excellent farmers. They knew all about irrigation. They built temples which were afterwards copied by the Greeks and which served as the earliest models for the churches in which we worship nowadays. They had invented a calendar which proved such a useful instrument for the purpose of measuring time that it has survived with a few changes until today. But most important of all, the Egyptians had learned how to preserve speech for the benefit of future generations. They had invented the art of writing. We are so accustomed to newspapers and books and magazines that we take it for granted that the world has always been able to read and write. As a matter of fact, writing, the most important of all inventions, is quite new. Without written documents we would be like cats and dogs, who can only teach their kittens and their puppies a few simple things and who, because they cannot write, possess no way in which they can make use of the experience of those generations of cats and dogs that have gone before.