Discourses, "That We Ought Not to be Angry with Men; and What Are the Small and the Great Things Among Men" (§4)

“Whoever then clearly remembers this, that to man the measure of every act is the appearance (the opinion), whether the thing appears good or bad. If good, he is free from blame; if bad, himself suffers the penalty, for it is impossible that he who is deceived can be one person, and he who suffers another person—whoever remembers this will not be angry with any man, will not be vexed at any man, will not revile or blame any man, nor hate, nor quarrel with any man.”