I remember when a few years ago I bumped into Beginning Scala by David Pollak. At the time I had no idea how this book would impact my future choices on which programming languages to learn, which technologies to invest my time in, and what I consider "good stuff" in general. Reading it must have been one of these movie-like moments of enlightment, with a heavenly beam of light striking you from above Mr. Bean style. Even today I can clearly remember the title of chapter that made the strongest impression. It was Collections and the Joy of Immutability. Read more.