Meditations is a series of personal writings by Marcus Aurelius, Roman Emperor 161–180 CE, setting forth his ideas on Stoic philosophy. Marcus Aurelius wrote the 12 books of the Meditations as a source for his own guidance and self-improvement. His stoic ideas often involve avoiding indulgence in sensory affections, a skill which, he says, will free a man from the pains and pleasures of the material world. He claims that the only way a man can be harmed by others is to allow his reaction to overpower him. An order or logos permeates existence. Rationality and clear-mindedness allow one to live in harmony with the logos.