Marcus Aurelius was a Roman emperor and Stoic philosopher. Stoicism is a philosophy that advises people to find happiness by living in harmony with the universe and by doing their best to create a better world, without worrying about things they cannot control.
His only significant philosophical work is his Meditations, which he wrote late in life whilst Roman emperor, possibly in the midst of the Parthian war. He died of plague after ruling for almost 20 years. He was a good ruler despite ruling through particularly difficult times, and suffering many personal problems.
"The happiness of your life depends on the quality of your thoughts."1
His Meditations (or Writings to Himself) are important in that they represent teachings of ethical behavior along Stoic lines, with a religious dimension. He wrote, "The happiness of your life depends on the quality of your thoughts; therefore, guard accordingly, and take care that you entertain no notions unsuitable to virtue and reasonable nature."
Marcus Aurelius was influenced by Plato, and their definitions of how happiness is achieved seem to overlap. Plato believed that happiness was based on being just (and accepting that justice does not always lead to pleasure) with the three parts of the psyche, reason, the will, and the appetite, being in balance. All unjust behaviors being empty, meaningless images, conjecture, and ignorance and therefore the source of the deepest unhappiness.
Marcus Aurelius believed that happiness is found when we fully accept nature, society, and ourselves; when we engage in complete self-absorption; and when we exercise our daily duty to others and to society.
He believed that if we refuse to accept nature as it is, we needlessly use our energy up and become upset when we realize that we cannot predict and control everything. When we focus our energies on the outside (external reality searching for the ideal self) as opposed to the inside (internal reality recognizing the real self), we fall victim to the disappointments inherent in empty, meaningless material goods, short lived pleasures, and false opinions. By continually interfering with the natural processes of life we run the risk of repeated disappointments, and true unhappiness.
I have often wondered how it is that every man loves himself more than all the rest of men, but yet sets less value on his own opinion of himself than on the opinion of others.2
Despite his Meditations displaying a view of life in keeping with Christian doctrine, his conception of providence, his recognition of his own imperfections, his focus on the control of desires, the rule of Marcus Aurelius appears to have overseen the persecution and execution of Christians.
For more information about the great philosophers and their views on narcissism and happiness, read Finding Happiness.
1, 2 Marcus Aurelius (Meditations)