While ruler of the Roman Empire during its greatest period, Marcus Aurelius practiced a simple, even austere personal lifestyle based on the sincere belief in Stoic philosophy, which emphasized the overwhelming importance of spiritual and intellectual values over physical or material pleasures. Noted publicly for his restraint, modesty, and nobility, Marcus Aurelius devoted many of his private hours to writing his Meditations, which contained the essence of his version of Stoic ethics. The core of his ethical beliefs may be summed up in a few basic rules: forgive others for their wrongs; be aware of the harm done to people by their own bad actions; avoid judging others; be conscious of your own faults; consider that you cannot know the inner thoughts of others; avoid anger, for life is brief; anger and grief can be worse than actual physical harm; and kindness and friendship are best for all. Although these rules are hardly revolutionary in theory, they assumed and retain importance because they were held by a Roman emperor.