That fact will explain to you why Mesopotamia was so very popular with the inhabitants of the northern mountains and the southern desert. It is a well-known fact that all living beings like to be comfortable. When it rains, the cat hastens to a place of shelter. When it is cold, the dog finds a spot in front of the stove. When a certain part of the sea becomes more salty than it has been before (or less, for that matter) myriads of little fishes swim hastily to another part of the wide ocean. As for the birds, a great many of them move from one place to another regularly once a year. When the cold weather sets in, the geese depart, and when the first swallow returns, we know that summer is about to smile upon us. Man is no exception to this rule. He likes the warm stove much better than the cold wind. Whenever he has the choice between a good dinner and a crust of bread, he prefers the dinner. He will live in the desert or in the snow of the arctic zone if it is absolutely necessary. But offer him a more agreeable place of residence and he will accept without a moment's hesitation. This desire to improve his condition, which really means a desire to make life more comfortable and less wearisome, has been a very good thing for the progress of the world. It has driven the white people of Europe to the ends of the earth. It has populated the mountains and the plains of our own country. It has made many millions of men travel ceaselessly from east to west and from south to north until they have found the climate and the living conditions which suit them best. In the western part of Asia this instinct which compels living beings to seek the greatest amount of comfort possible with the smallest expenditure of labor forced both the inhabitants of the cold and inhospitable mountains and the people of the parched desert to look for a new dwelling place in the happy valley of Mesopotamia. It caused them to fight for the sole possession of this Paradise upon Earth. It forced them to exercise their highest power of inventiveness and their noblest courage to defend their homes and farms and their wives and children against the newcomers, who century after century were attracted by the fame of this pleasant spot. This constant rivalry was the cause of an everlasting struggle between the old and established tribes and the others who clamored for their share of the soil. Those who were weak and those who did not have a great deal of energy had little chance of success. Only the most intelligent and the bravest survived. That will explain to you why Mesopotamia became the home of a strong race of men, capable of creating that state of civilization which was to be of such enormous benefit to all later generations. THE SUMERIAN NAIL WRITERS