When reading history books, one of the great advantages is that when encountering something, you can gradually sort out your thoughts through the healing of time, learn to calm your emotions, and after the event, learn to reflect and understand what you have learned from it.
Previously, you might get angry and think for a long time, but now, when you have an emotion at the beginning, gradually your heart starts to calm down. Instead, you are completely purified from inside out, making your heart stronger.
Because you finally understand that in life, apart from life and death, everything else you have experienced are just scratches.