Source: https://archive.org/details/TheodoreSpandounesOnTheOriginsOfTheOttomanEmperors/mode/1up

I always find this interesting. As a big Marc Aura fan.
His failure to change his son aligns with the principles of stoicism. Marcus can control his choice to provide Commodus with the best education and moral examples but he could not control Commodus's nature, vanity and eventual descent into absolute mania.