Meditation 9.42
42. Whenever you are offended by a man's shamelessness, ask yourself immediately: 'Is it possible then for the shameless not to be in the world?' It is not; do not then ask for the impossible; for he, too, is one of the shameless who must exist in the world. And have the same ready also for the rogue, the traitor, and every kind of wrongdoer; for directly you remind yourself that the class of such persons cannot but be, you will be gentler to them as individuals. Another useful thing is to call to mind immediately what virtue Nature gave man to meet this wrong, for she gave as an antidote against the unfeeling, mildness, against another, some other faculty, and generally speaking it is in your power to convert the man who has gone astray, for every man who does wrong is going wrong from the goal set before him and has gone astray. And what harm have you suffered? For you will find that none of those with whom you are angry has done the kind of thing by which your understanding was likely to become worse and it is there that your ills and harms have their entire existence.
How is it an evil or strange event that the uninstructed does what uninstructed men do? See whether you should not rather find fault with yourself for not expecting that he would do this wrong; for you had aptitudes from reason to enable you to argue that in all probability this man will do this wrong, and yet you forgot and are surprised that he did wrong.
But, most important of all, turn inward to your own self, whenever you blame the traitor or the ungrateful, for the fault is plainly yours, whether you trusted a man with such a disposition to keep faith or whether, when you bestowed a favour, you did not give it unreservedly or so that you received the whole fruit from your act itself then and there. For when you have done good, what more, oh man, do you wish? Is it not enough that what you did was in agreement with your nature and do you seek a recompense for this? As if the eye asked a return for seeing or the feet for walking; for just as these were made for this which they effect according to their proper constitution, and so get what is theirs, even thus man is made by Nature to be benevolent, and whenever he contributes to the common stock by benevolence or otherwise, he has done what he was constituted for, and gets what is his own.