These passages from Seneca and Marcus Aurelius are worth comparing. Seneca sounds like he’s potentially quoting an earlier author at one point. A very similar passage exists in Marcus’ later Meditations. One possibility may be that both authors are referring to a common, earlier, source, which Marcus is paraphrasing.
The wise man will not be angry with sinners. Why not? Because he knows that no one is born wise, but becomes so: he knows that very few wise men are produced in any age, because he thoroughly understands the circumstances of human life. Now, no sane man is angry with nature: for what should we say if a man chose to be surprised that fruit did not hang on the thickets of a forest, or to wonder at bushes and thorns not being covered with some useful berry? No one is angry when nature excuses a defect. The wise man, therefore, being tranquil, and dealing candidly with mistakes, not an enemy to but an improver of sinners, will go abroad every day in the following frame of mind: “Many men will meet me who are drunkards, lustful, ungrateful, greedy, and excited by the frenzy of ambition.” He will view all these as benignly as a physician does his patients.— Seneca, On Anger, 2.10
Begin the morning by saying to thyself, I shall meet with the busy-body, the ungrateful, arrogant, deceitful, envious, unsocial. All these things happen to them by reason of their ignorance of what is good and evil. But I who have seen the nature of the good that it is beautiful, and of the bad that it is ugly, and the nature of him who does wrong, that it is akin to me, not only of the same blood or seed, but that it participates in the same intelligence and the same portion of the divinity, I can neither be injured by any of them, for no one can fix on me what is ugly, nor can I be angry with my kinsman, nor hate him, For we are made for co-operation, like feet, like hands, like eyelids, like the rows of the upper and lower teeth. To act against one another then is contrary to nature; and it is acting against one another to be vexed and to turn away.— Marcus Aurelius, Meditations, 2.1