Meditations
Marcus Aurelius
Written by Marcus Aurelius, one of the greatest Roman Emperors that ever ruled. Meditations is the personal diary of Marcus Aurelius. It explores his philosophies, which circulate around Stoicism.
It is a book with an interesting perspective, because it follows the life of one of the most powerful people in the world at the time. This lets you see into the mind of how someone with that level of leadership and intellect manages people on a day to day basis.
One of his most notable quotes, "teach or tolerate", is a testament to how intelligent he was as a leader. Being able to boil down complex human action into a binary decision is not an easy thing to do.