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 :)
