Revision with unchanged content. The history of economic is a subject that is huge! There are thousands and thousands of pages, hundreds of books, and hundreds of scholars that have contributed to the subject of economic thought. In fact, most higher learning textbooks require at least two semesters (one year) of study to get through them. This book simply attempts to capture some of the most significant contri?butions made to economic thought as dictated by some of the most renowned scholars. The purpose of this book is to provide key contributions made by economic scholars, especially since the time of Adam Smith. Although this book does not cover all details, ideas, and thoughts held by all economic scholars, it is designed specifically to help undergraduate students and anyone not previously acquainted with economic doctrine or the history of economic thought to quickly acquire the views of these scholars. This book can be a great resource for use in one-semester undergraduate course for economic doctrine or history of economic thought. It also can be a great tool for anyone desiring to gain a better appreciation for how the field of economics has evolved in the past couple of centuries.