If you've ever studied foreign policy or international affairs, you're familiar with the ideas and theories of Hans Morganthau, even if you don't realize it. He defined power for this field (no, really-- his definition of power is the accepted standard in the field), and much of modern international affairs theory is based on his ideas. This book is written as a textbook, but a rather readable one. For serious students of international affairs, much of the contents of the book may seem like a review, but I still found several ideas that were new to me. For beginners or those who simply wish to increase their knowledge of world politics, this book may seem like a somewhat dense read, but it will teach you 90% of modern international affairs theory. Well worth the money and the effort.