What is the theme in The Theory of the Leisure Class by Thorstein Veblen?

The Theory of the Leisure Class is a book about economics, in spite of Veblen's style of writing. Even though there is no use of the terms demand and supply, the book is an analysis of the modern lifestyle in Veblen's time. Veblen is analyzing the economic life of societies. He is studying the class distinctions that exist in society and where they came from. How did the leisure class develop? How did the institution of property come into being and why?