It’s one of the most popular and most misunderstood business concepts of our time. Since the term Lean Production was first popularized in 1990, lean has come to mean very different things to different people. In this paper, we go back to the origins of Lean Production - an alternative business approach pioneered by Toyota Motor Corporation - and present insights into how Toyota actually developed a learning system to gain competitive advantage through the continuous development of people, rather than simply designing and optimizing an efficient production system. We draw on our observations from Toyota plants around the world and our discussions with various Toyota sensei, and present a framework for understanding lean as a learning system, not a production system.