If you are told that such a one speaks ill of you, make no excuses against what was said, but answer, "He was ignorant of my other faults, else he would not have mentioned these alone!"
Epictetus (~55 — ~135) was a Romano-Greek philosopher who lived during the reigns of Nero, Domitian, and Hadrian, as the Roman Empire was slowly collapsing. No writings by Epictetus are known—his discourses were transcribed and compiled by his pupil, Arrian. Many versions of the above quotation float across the web. For me, this one is the strongest.
His work is largely concerned, from what I understand, with distinguishing between those things in our power (prohairetic things) and those things not in our power (aprohairetic things).
Why I love this quotation: so much in life is, or can be, dictated by caring about other people's perceptions. And here, ~2000 years on, is an idea from a man, born a slave, deliberately crippled, it is believed, by his master. But--his mind was slave to none.
Obviously Epictetus knew that long before he gained his freedom.