Someone that I respect in software development recommended this book to me. Pragramatic Thinking & Learning by Andy Hunt. I got it in the mail last evening and have already read half of it. He talks about the Dreyfus Model Stages. These stages apply to any profession and were first implemented in the early 1980s with nurses. He says skills in a profession are distributed in 5 levels from lowest to highest: Novice, Advanced Beginner, Competent, Proficient, and Expert. Most people don't get past Advanced Beginner. After reading this chapter I now see why implementation of agile will likely fail if any of the team members are at the Novice or Advanced Beginner stage. I would recommend to any developer interested in maximizing their skills and mental sharpness read this book. It is an enjoyable book to read as well.