This document discusses how Lean and Scrum have developed and influenced one another over time. It traces the origins of concepts like scientific management, the Toyota Production System, and agile software development. Key influences included the Hawthorne Experiment, Training Within Industry program, Toyota's approach to developing people, and the emergence of patterns languages. These ideas evolved in parallel and helped shape one another, with Lean product development and Scrum each incorporating insights from the other field. The document advocates for continuing to learn, practice, and create reusable knowledge to improve processes and organizations.