If you are at all interested in the history of philosophical or theological thought, then you will want to acquaint yourself with the writings of Marcus Aurelius. In this work addressed to himself (he originally entitled it "To Myself" and it later came to be known as the "Meditations") he distills the essence of Stoicism, one of the most important and influential schools of classical philosophy. The Staniforth translation combines elegance and clarity, and the introduction and notes are excellent, so the Penguin edition is probably the one to go for, although some readers favour the Hays translation, which is more direct and colloquial. Staniforth argues persuasively that Stoicism formed the rational basis for the fledgling Christian theology. (Interestingly, there is one, rather disparaging, reference to Christians in the text, which I suppose illustrates how significant the movement had become, a century after the death of its founder. Many scholars believe this to be an interpolation by a later author). Indeed, the similarity of this work to the late medieval "The Imitation of Christ" is striking. Part of the fascination of "Meditations" lies, of course, in the fact that Marcus was emperor of Rome, the greatest power on Earth at that time. We thus get an insight into the mind of an important historical character. This also means that much of what occupied him is hardly relevant to you or me. How many of us are plagued with sycophantic courtiers, or need to remind ourselves that the adulation of the mob may be short-lived? Yet it is clear that, despite all his power and privilege, Marcus was a troubled and pensive soul. One might say that "Meditations" is Stoicism for monarchs, whereas "The Imitation" is Stoicism for monks. If you enjoy one of those books, the chances are you will enjoy the other.