As I read through Marcus Aurelius’ Meditations I’m reminded that Truth, having a single source, can be expressed through different ages, mediums, and speakers, but you’ll still recognize it as Truth. No matter what our differences–circumstances, social status, occupation, location, etc–we all exist within the same nature and under the same rules.
What you end up getting is pagan emperors who speak like Taoist philosophers who speak like Renaissance saints. There is only one Truth so the same Truth has been revealed to each, however culturally or temporally disparate.
There are many examples in Meditations, but the one I encountered today is on page 123 of the Modern Library edition translated by Gregory Hays. Marcus Aurelius writes:
When you face someone’s insults, hatred, whatever…look at his soul. Get inside him. Look at what sort of person he is. You’ll find you don’t need to strain to impress him.
But you do have to wish him well. He’s your closest relative. The gods assist him just as they do you–by signs and dreams and every other way–to get the things he wants.
This immediately reminded me of the words of the Catholic saint Thomas More:
Bear no malice or evil will to any man living. For either the man is good or wicked. If he is good and I hate him, then I am wicked. If he is wicked, either he will amend and die good and go to God, or live wickedly and die wickedly and go to the devil. And then let me remember that if he be saved, he will not fail (if I am saved too, as I trust to be) to love me very heartily, and I shall then in like manner love him. And why should I now, then, hate one for this while, who shall hereafter love me forever, and why should I be now, then, an enemy to him with whom I shall in time be coupled in eternal friendship? And on the other side, if he will continue to be wicked and be damned, then is there such outrageous eternal sorrow before him that I may well think myself a deadly cruel wretch if I would not now rather pity his pain than malign his person.
At the root of both Stoicism and Catholic doctrine is the truth that we all share one nature and we were made to be in communion with one another. We are social, we are each parts of a single body. They both also acknowledge a fallenness of human nature. The fallenness is explicitly shown in Catholicism with Adam and Eve eating the forbidden fruit and sin entering the world. It is more implicitly shown in the writings of Marcus Aurelius. If Marcus Aurelius himself didn’t experience this fallen nature, why would he constantly remind himself in his personal writings that the Logos has ordered the universe and that the best a man can do is to fulfill his purpose as ordained by nature. If not fallen, he wouldn’t need to constantly remind himself.
In both cases, there is some ideal of human nature which we aren’t reaching, or aren’t able to reach. That being the case, both quotes regard others as our "closest relatives". We all suffer from this sickness of sin and fallenness, this inability to perfectly align ourselves with "Nature" or "the Logos" or "the Will of God" and to act out our part as we were made to act it out. And we suffer because of this. Thus you have both of these men reminding themselves not to return hatred for hatred. Both know that the divine is working for the salvation of every man ("The gods assist him as they do you…", "…if he be saved, he will not fail…to love me very heartily…") and that humanity was intended to be one body in harmony with one another. There’s no place for hatred in that equation.
The essential truth is that we are all heading toward the same destination, which is Judgement Day, and we should all want for ourselves and everyone we know to have chosen good over evil, virtue over vice. Some will, some won’t. And as Thomas More says, for those who don’t make the proper decision and try to align their fallen nature with their intended nature, we would be deadly cruel not to pity their pain rather than malign their person. Because what awaits them is hell, a misery which they have chosen since they will have chosen not to be part of the harmonious body and not to live as they were made to live.
Those who throw insults and hatred at us can never harm us because they can never harm our "mind" (as Aurelius might say) or our "soul" (as More might say). We wish them well, but we don’t waste our time repaying hatred for hatred, or evil for evil.
Either we will be made right with one another in the end, or our present enemies will be lost forever. Hatred and retaliation are made cruel and unnecessary in either case.