When any person treats you ill or speaks ill of you, remember that he
does this or says this because he thinks that it is his duty. It is not
possible then for him to follow that which seems right to you, but that
which seems right to himself. Accordingly if he is wrong in his
opinion, he is the person who is hurt, for he is the person who has
been deceived; for if a man shall suppose the true conjunction to be
false, it is not the conjunction which is hindered, but the man who has
been deceived about it. If you proceed then from these opinions, you
will be mild in temper to him who reviles you; for say on each
occasion, It seemed so to him.