Between years, I was finally able to get into Clean Agile by Robert C. Martin. Uncle Bob impressively describes the history of agile software development. From its beginnings at the signing of the agile manifesto until today. The book is an excellent practical summary of twenty years of agile development that provides background and context from one of the agile manifesto's first signers.
Uncle Bob shows the connection between software craftsmanship and the agile manifesto. Critically, the evolution of agile software development. Business consultants increasingly dominate a simple process model by software developers for software developers. I share Robert C. Martin's opinion that agile models like Scrum should be simple for the software development team.
The idea of a process model on a beer coaster appealed to me more than ten years ago. Afterward's, I realized that agile development requires much discipline and focus on customer value. Clean agile methods are the software process models with the most business benefit I've ever known.