As scientists and learned people may know or ponder, knowledge has invariably made prodigious journeys. What it may seem to us just a leap in time often turns out to be a long progression from place to place, form one city to another. For instance, the caravans of the middle east which carried with their merchandise the methods of trade of their countries—the weights and measures, the methods of reckoning—and techniques and ideas went where they went, through Asia and North Africa. In this fashion, the mathematics of Pythagoras has not come to us directly. First, it fired the imagination of the Greeks, but then, the very place where it was formed into an orderly system was the Nile city of Alexandria around 300 b.C. And the man who made the system, and made it famous, was Euclid.