Here we cover similar ground to part 5's "Men are disturbed not by the things which happen, but by the opinions about the things".
Remember that it is not he who reviles you or strikes you, who insults you, but it is your opinion about these things as being insulting. When then a man irritates you, you must know that is is your own opinion which has irritated you. Therefore especially try not to be carried away by the appearance For if you once gain time and delay, you will more easily master yourself.
I find the last line particuarly useful. In part 10 we had "And if you have been thus formed to the proper habit, the appearances will not carry you along with them". Again, this part is about breaking the habit of automatic reaction; training yourself in a way that gives you the time to employ your Stoic reason before reactive emotion carries you away.