Economics is a study of mankind in the ordinary business of life.” So wrote Alfred Marshall, the great 19th-century economist, in his textbook, Principles of Economics. Although we have learned much about the economy since Marshall’s time, this definition of economics is as true today as it was in 1890, when the first edition of his text was published. Why should you, as a student at the beginning of the 21st century, embark on the study of economics? There are three reasons. The first reason to study economics is that it will help you understand the world in which you live. There are many questions about the economy.