The Meditations of Marcus Aurelius
This book is difficult for me to describe succinctly. It’s had a tremendous impact on my life and I honestly no longer remember the number of times I’ve read it. Especially the first book (it is subdivided into twelve parts, or books).
These are quite literally, the meditations of Marcus Aurelius. He writes his own private thoughts about duty and the meaning of life, reminds himself to stay true to his values, to be a good man, to be humble, to give thanks to everyone and everything that formed him. He writes as a man, as a Roman and as an emperor who has doubts, questions and who struggles with his existence and attempts to remain stoic in the face of that internal dissonance – both on a philosophical level, and on a simpler human level.
While there is some discussion of his life, this is far from a biography and I have found his writing and perspective to be extremely enlightening and comforting during difficult times.
If I could read only one book for the rest of my life, it might very well be this one.
You can find an online copy here, courtesy of MIT (there is also a link to a text only version).
Amazon also has several different editions available, some of them for very little (I bought this one recently for a couple bucks).