The speaker looks up to whomever they are talking to as they are kind to those who deserve it. The speaker then states that “If people were always kind and obedient to those who are cruel and unjust, the wicked people would have it all their own way; they would never feel afraid, and so they would never alter, but would grow worse and worse” which speaks for itself; if cruel people never learned a lesson they would remain cruel or worsen.
In the last part the speaker continues “When we are struck at without a reason, we should strike back again very hard; I am sure we should - so hard as to teach the person who struck us never to do it again” which, again, is pretty self-explanatory. If someone is rude to them they will teach them a hard lesson to scare them into never doing it again.