Of all the Roman emperors, Marcus Aurelius is perhaps one of the best examples of the uses of Philosophy to be a successful ruler. He wrote his personal philosophy and everything he learned throughout his life in a book called "Meditations".
It's an interesting read for those who enjoy philosophy in general, and classical philosophy in particular, since the family and tutors of Marcus Aurelius presented him with the best of classical thought from Greece, Rome, and other areas of the Empire.
This official edition is coming from Dawsons RSP Publishing and it is the best one we could find out there. It has an accurate translation without the common mistakes of the old editions. Hope you enjoy it!