Not sure if it is necessarily Mustachian, but it has put me in a good place overall, was Peter Lynch, "Beating the Street". It made so much sense to me and launched a very profitable love affair with becoming FI. And, how I tie it together with being Mustachian is, now that I'm rich, I'll do better about those root causes that I have drifted away from in my 20's and 30's... Just like Gates probably didn't necessarily plan to wipe out age-old diseases like polio and malaria when he was dominating the user interface and software wars, I had to lose my focus on what I cared about to survive, but I'm back on the top of the pyramid and want to use the rest of my life to do good.