ABSTRACT
Comparison is the basis of much of what we know about the world. Astronomers compare Earth with other planets to explain why the size of our globe and its distance from the Sun allow life to flourish. Biologists study the physiology of other species for clues about how the human organism functions and how diseases can be combated. Economists often contrast the performance of one economy with reference to others, determining why some countries experience growth and prosperity while others encounter stagnation and poverty.
