"The universe is transformation: life is opinion."
"How much trouble he avoids who does not look to see what his neighbor says or does or thinks, but only to what he does himself, that it may be just and pure; or as Agathon says, look not round at the depraved morals of others, but run straight along the line without deviating from it."
"For the greatest part of what we say and do being unnecessary, if a man takes this away, he will have more leisure and less uneasiness. Accordingly on every occasion a man should ask himself, Is this one of the unnecessary things? Now a man should take away not only unnecessary acts, but also, unnecessary thoughts, for thus superfluous acts will not follow after."
"In a word, thy life is short. Thou must turn to profit the present by the aid of reason and justice. Be sober in thy relaxation."
"Love the art, poor as it may be, which thou hast learned, and be content with it; and pass through the rest of life like one who has entrusted to the gods with his whole soul all that he has, making thyself neither the tyrant nor the slave of any man."
"Time is like a river made up of the events which happen, and a violent stream; for as soon as a thing has been seen, it is carried away, and another comes in its place, and this will be carried away too."
"Do not then consider life a thing of any value; for look to the immensity of time behind thee, and to the time which is before thee, another boundless space. In this infinity then what is the difference between him who lives three days and him who lives three generations?"
And one of my favorite:
"But perhaps the desire of the thing called fame will torment thee.—See how soon everything is forgotten, and look at the chaos of infinite time on each side of the present, and the emptiness of applause, and the changeableness and want of judgment in those who pretend to give praise, and the narrowness of the space within which it is circumscribed, and be quiet at last. For the whole earth is a point, and how small a nook in it is this thy dwelling, and how few are there in it, and what kind of people are they who will praise thee."
-Marcus Aurelius