Aaaah, a couple of ones that jump to mind:<p><i>Atlas Shrugged</i> and <i>The Fountainhead</i> by Ayn Rand. I prefer the latter, but they're both great books. I discovered Rand later in life, after a lot of my beliefs were probably already pretty well locked in, but her outlook certainly resonates with me, and the inspiration I found in her books helps nudge me in the direction of truly to live my life more fully as <i>my</i> life, not someone else's idea of what my life should be.<p><i>The Selfish Gene</i> - Richard Dawkins. I was already a borderline atheist anyway, although I tended to use the term agnostic to avoid arguing with friends & family, considering that I live in the Bible Belt. But Dawkins' book showed me a counter argument to the "irreducible complexity" argument that made sense on a very fundamental level, and IR was one of the last things that kept even a vestige of "mystical" thought alive in me. After reading this book, I felt very comfortable in being an atheist, and I also decided to quit dodging the issue and start telling people that I'm atheist, whether they like it or not. Also, see above: I'm not interested in living a life that's about trying to please other people. I get one crack at this, and it's fairly short. This is my life, damnit.<p><i>The World Is Flat</i> - Thomas Friedman. Considering that I was already a libertarian leaning, pro free-markets / free-trade type, you might think that his book would have had little impact on me. But it actually made me a lot more aware of the various implications (pro and con) of globalization. Largely, though, it reinforced my thinking that globalization is - over the long term - a mostly good thing. It will hurt some individuals in the short-term, but it also creates a lot of opportunities.<p>But beyond all those, the one book that I consider the single most life-changing book of all... the book that I'd probably refer to as my Bible if I didn't get a bit queasy about even making that joke:<p><i>The Four Steps To The Epiphany</i> - Steve Blank. As an aspiring entrepreneur, I had some ideas I was working on, and some plans to do a startup a while back. But I really had NO idea of the process of going from "an idea" to "a company" much less a profitable, growing, scalable company.<p>Reading TFSTTE felt like "taking the Red pill". Now I see the path from "idea" to "company" far, far more clearly than I ever did before. And while it's no guarantee of success, the process that Steve lays out feels like the closest thing you could get to a "paint by numbers" approach to building a business. We've been working through the Customer Development Methodology for a while now, and I'm pretty sold on it's value. And we haven't even always done it right (for various reasons).