Marcus Aurelius (AD 121-180) was, of course, the Roman emperor, and we find this reflected in his notes to himself, which were written while on military campaign in the last decade of his life. When the emperor Hadrian began to take thought for succession, he formally adopted Aelius Antoninus (usually known as Antoninus Pius), but on condition that Antoninus also adopt Marcus Aurelius and Lucius Verus as his heirs. Marcus had considerable difficulty adjusting to his position; he never seems to have particularly liked either the duties or the pomp that his adoption gave him, a fact that was probably aggravated by the fact that he was never in very good health. Through much of his reign the northern borders of the empire were in serious peril, and dealing with the tribes to the north took a considerable portion of his last years. His campaign was successful, but was never completed as he fell ill.
The work that has come down to us has no definite title and may never have been intended to have any. The earliest title in the manuscripts seems to have been "To Himself" (ta eis heauton). There are two indications in the text of location and time ("Written in the land of the Quades, on the banks of the Gran" and "Written in Carnutum"); we do not know if they are original or not. The book is usually divided into twelve books, but the divisions seem artificial and are certainly later; Hadot notes that the Vaticanus manuscript only indicates the divisions Book I, Book II, Books III-IV, Books V-VI-VII-VIII, Books IX-X-XI, and Book XII. As a set of notes that seem to have been written on different occasions, it involves a great deal of repetition; but one way to look at the work is as Marcus's constant refining of Stoic ideas in light of his practical experience. (This is, I think, the appropriate answer to claims of Marcus Aurelius's not being a work of 'original' philosophy, which I find come up amusingly often. In fact, the philosophical work here could hardly help but be original: it is a case of a philosopher writing in unusual circumstances -- not many philosophers have had to struggle with ethical issues while on military campaign as emperor -- in a format that itself is relatively uncommon, and he is trying out various ideas from different directions and looking at them in different lights. It is true that many of the central ideas are from Epictetus and other Stoics; but he is doing very different things with them. And while one might claim that Marcus Aurelius is not of the intellectual influence and significance of a Plato or Aristotle, it is an atrocious intellectual habit to talk as if the good were the enemy of the best.)
You can read the Meditations online in English in George Long's translation at the Internet Classics Archive.
Book I, being more coherent and organized than the other parts of the work, is often thought to have been written last. In it Marcus goes through the resources he has received from the people in his life -- usually their example, but occasionally other thing as well. Some comments about the people mentioned (several of them are people about whom we otherwise know little):
Verus and Annius Verus: Marcus's father, Annius Verus, died when he was an early teenager, so his grandfather, Verus, had a significant role in his life, and he did not know his father except through some limited memories and by reputation.
Domitia Lucilla: Marcus's mother; from an extraordinarily wealthy family, she seems to have been quite capable, and, of course, she raised Marcus herself for a considerable portion of his late childhood.
Quintus Junius Rusticus: A Stoic philosopher. Outside of his association with Marcus, he is best known for probably being the judge who condemned St. Justin Martyr to death.
Apollonius of Chalcedon: Another Stoic philosopher.
Sextus of Chaeronea: Another Stoic philosopher. He seems to have been related to Plutarch, and also seems to have been a later rather than earlier acquaintance of the emperor, since we have stories of Marcus as an old man studying with him.
Alexander of Cotiaeum: A grammarian. Outside of his association with Marcus, he is best known for being the teacher of Aelius Aristides, one of the greatest orators of the Second Sophistic.
Marcus Cornelius Fronto: Born in Numidia, he became very wealthy and was appointed tutor to Marcus by Antoninus Pius. He had a very close relationship with Marcus, and some of their extensive correspondence has survived. Minucius Felix in the Octavius briefly mentions a speech in which he attacks Christians for incestuous orgies.
Alexander the Platonist: He was one of Marcus's secretaries.
Claudius Severus: We don't actually know who Marcus intends, but he likely means Claudius Severus, whose son married one of Marcus's daughters, and who might possibly have been a Peripatetic philosopher.
Claudius Maximus: He seems to have been another Stoic philosopher.
Antoninus Pius: Marcus's adopted father and, with Marcus, one of the Five Good Emperors. Famous for his dutifulness, he had a relatively peaceful reign, during which he patronized philosophy and the arts, and seems to have had a relatively hands-off approach to governing the empire, preferring to handle matters through the local authorities.
Note that Marcus's last note, on what he has received from the gods, sums up the rest of the book.
to be continued