For me one of the most important books of the past decade, both as a magician and a person, is Daniel Kahneman's Thinking Fast and Slow. As a magician, it taught me how to take advantage of the natural ways in which the brain processes information to deliver magic in a more powerful and mystifying way.
As a person, it made me a better problem solver and, when I was tutoring, a better teacher. I knew that in order for my students to perform effectively, I had to make sure they were "thinking slow" in order to use the problem solving skills they had rather than just blurting out the first thing that popped into their heads and calling it a day.
Here is a tiny look into what was a truly life-changing book. Speaking at Google, Prof. Daniel Kaheman:
During his introduction, they mention that Kahneman is a Nobel Prize winner. I didn't know that when I started reading the book. Then, nearly exactly halfway through, it jumped off the page, "the research for which we won the Nobel prize." Talk about burying the lead.