Summary
Marcus Aurelius emphasizes that when a person commits an unjust or immoral act, they ultimately harm themselves. By engaging in wrongdoing, they corrupt their own character, and in doing so, they become a worse version of themselves.
Interpretation
In real life, this could be understood through the example of dishonesty. If someone constantly lies to get ahead, they may gain short-term benefits, but over time, they erode their integrity and self-respect. Their reputation may suffer, and internally, they may feel guilt or lose confidence in themselves. By acting unjustly, they are not just wronging others but also damaging their own moral foundation and happiness.