If you're looking for a certain portion of this excerpt that restates the main idea, I would have to say that the first few words explain it very well: "<span>I demand that my books be judged with utmost severity..." The writer of this statement is saying that they wish for their books to only be judged by those who are educated in grammar and logic. </span>
I think that this means that not everyone has the same mentality, so therefore, the same event can mean different things to different people. For example, every person experiences life differently whether that be different cultures, environments, or religion. This all affects how a person develops moral, ethics and their thinking process. Also, people learn new things every day which can also influence their , already existing, mentality meaning "[their] response can change over time.
not 200 words but i hope this helps :)