From the author: "There is clearly much to learn from the fluctuating fortunes of particle physics and , upon my retirement in 1987, I decided to write a book that would record my personal assessment of what had taken place in the conceptual evolution of modern particle physics during my own scientific lifetime, especially during the "heroic period". The writing of the book turned out to be a major "voyage of discovery", of brilliant theoretical insights and ingenious experiments, that completely transformed particle physics by 1980."