The happiness of your life depends upon the quality of your thoughts: therefore, guard accordingly, and take care that you entertain no notions unsuitable to virtue and reasonable nature.

He ruled with Lucius Verus as co-emperor from 161 until Verus' death in 169. Tutor Fronto and various Antonine officials survives in a series of patchy manuscripts covering the period from c. 138 to 166.

Marcus Aurelius' Stoic tome Meditations written in Greek while on campaign between 170 and 180 is still revered as a literary monument to a philosophy of service and duty describing how to find and preserve equanimity in the midst of conflict by following nature as a source of guidance and inspiration. He was the last of the Five Good Emperors and is also considered one of the most important Stoic philosophers.