BUT, you may say: suppose we agree that some sort of knowledge of history is essential for an adult understanding of the world, what actually belongs in our classrooms? The varieties of history are enormous; facts and probabilities about the past are far too numerous for anyone to comprehend them all. Every sort of human group has its own history; so do ideas, institutions, techniques, areas, civilizations,and humanity at large. How to begin? Where to start? How bring some sort of order to the enormous variety of things known and believed about the past?