Marcus Aurelius

How much time he gains who does not look to see what his neighbor says or does or thinks, but only at what he does himself, to make it just and holy.

The happiness of your life depends upon the quality of your thoughts.

Whenever you are about to find fault with someone, ask yourself the following question: What fault of mine most nearly resembles the one I am about to criticize?

If you are distressed by anything external, the pain is not due to the thing itself, but to your estimate of it; and this you have the power to revoke at any moment.