The Meditations of Marcus Aurelius are a series of private reflections, written in Greek by the Roman Emperor for his own use, partly while on campaign defending the empire's Northern frontiers. Although not a work of theoretical philosophy, the twelve books of the Meditations are deeply influenced by stoic ethics. The contrast between Marcus Aurelius, perhaps the closest approach to the Platonic ideal of the philosopher-king, and his influential precursor, the freed slave Epictetus, has often been taken to exemplify the indifference of the Stoic ideal to external fortune.
The Meditations at Amazon
Free online texts
Gutenberg: The Meditations. Multiple formats.
Internet Archive: The Harvard Classics, Volume 2. Plato, Epictetus, Marcus Aurelius. The Apology, Crito and Phaedo, by Plato. The Golden Sayings by Epictetus. The Meditations by Marcus Aurelius. EPUB, MOBI, TXT & PDF formats.
Loebulus: L058 - Marcus Aurelius -- Communings with Himself of Marcus Aurelius Antoninus, Emperor of Rome. PDF of public domain Loeb edition in Latin and English.
University of Adelaide: The Meditations, translated by George Long. Multiple formats.
Wikisource: The Thoughts Of The Emperor Marcus Aurelius Antoninus, translated by George Long (1862). Multiple formats.
BBC In Our Time: Stoicism - radio discussion with Melvyn Bragg, Angie Hobbs, Jonathan Rée and David Sedley.
History of Philosophy without any gaps: The Philosopher King: Marcus Aurelius - podcast by philosopher Peter Adamson.
Internet Encyclopedia of Philosophy: Marcus Aurelius, by John Sellars.
Librivox: The Meditations - public domain audiobook.
Literature and History: Episode 74 - Marcus Aurelius. Podcast by Doug Metzger.
The Stanford Encyclopedia of Philosophy: Marcus Aurelius.
The Great Conversation: Further reading at Tom's Learning Notes.
Ancient Greek resources: Learn to read Greek classics in the original.