The autobiography of Ghandi. I try to re-read this book periodically. From diet, to the power of meditation, and the value of long reflective walks, this book is the example that I try to base my life upon.
This is a great book. It shaped my political life, in that it made me realize that humanity is estranged. Moreover, it made me realize that political solutions to social problems which do not reflect that reality will fail.
I can't afford to go to India, or Japan, and have a guru train me in meditation. However, this book is the next best thing. In very easy to understand language, it teaches one how to meditate and deals with all the problems a novice, such as myself, faces when trying to learn to meditate.
What can I say about this book, it's my writing guide. This books solves every problem a writer faces, from learning to avoid writing in passive voice, to learning how to recognize and avoid fragmented sentences. I owe much of my academic success to this book.
I would have added the Ralp Ellison's
The Invisible Man, too, but that's been mentioned enough.