We can't believe people used to go to public executions, or even that there was such a thing. But attendance was pretty much mandatory, and it's easiest to understand as a kind of edutainment. The takeaway was: “Here is why it's important to obey the rules.” An expedient way to reinforce social norms. We've got our own ways of horrifying the future. Forget about us eating animals, imprisoning huge numbers of our fellow citizens, moving two tons of metal to get one clerk to Walmart. Bad enough, but then there's this: We poop into large bowls of drinkable water.