Marcus Aurelius Antoninus was Roman emperor from 161 to 180 AD and a Stoic philosopher. He was the last of the rulers known, noncontemporaneously, as the Five Good Emperors and the last emperor of the Pax Romana, an age of relative peace, calmness and stability for the Roman Empire lasting from 27 BC to 180 AD. Meditations is a series of his personal writings, recording his private notes to himself and ideas on Stoic philosophy. He wrote the 12 books of the Meditations in Koine Greek as a source for his own guidance and self-improvement.