4 ideas
The series tells each period through the daily miseries of ordinary people, such as peasants, soldiers, child workers and prisoners, rather than through kings and treaties. Asking what it smelled like, what people ate, how they were punished and how they died shows a past full of bodily discomfort and routine cruelty. That picture is invisible when history is told as the achievements of rulers.
Gruesome, gross and forbidden-seeming details, such as torture, disease, toilets and executions, capture children's attention because they feel like things adults would rather not say. Once hooked by the revolting detail, readers take in the surrounding context, such as religion, economics and power, that explains why the detail existed. Transgression works as the delivery mechanism for ordinary historical understanding.
They kept the heart in the body because they believed it held thought and would be weighed in the afterlife. The case shows how a culture's beliefs about where the mind lives directly dictated its physical treatment of the dead.
It works as a gateway: it sends readers on to fuller sources, not as a final authority. The cost is that some simplifications or exaggerations get remembered as fact.