If a schoolboy suddenly finds himself transplanted to a new school in foreign parts, he is naturally puzzled by much of the curriculum. The study of languages and of subjects strongly depending on language, such as literature, changes radically from nation to nation, and some subjects, history for one, may even be interpreted differently in different parts of a single country. But in the sciences and in mathematics the boy will probably be quite a t home; for, even though order and fashion of presenting details may vary from place to place, these subjects are essentially international.

But if we now imagine our schoolboy transported not only to a different place but also to a different age—say to Greece two thousand years ago, or Babylonia four thousand years ago—he would have to look hard to find anything that he could recognize as science, either in content or in method. What was called “physics” in Aristotle's day, with its discussions of the number of basic principles and of the nature of motion, we would classify as philosophy; and its connection with modern physics appears only after a careful study of the development of the physical sciences. Mathematics alone would now look familiar to our schoolboy: he could solve quadratic equations with his Babylonian fellows and perform geometrical constructions with the Greeks. This is not to say that he would see no differences, but they would be in form only, and not in content; the Babylonian number system was not the same as ours, but the Babylonian formula for solving quadratic equations is still in use.