Apparently it’s “common sense” or whatever

Conduct books were specifically created so that people could learn how to act and behave in society. Sounds weird, but they became popular during the late middle ages, aka the time were people were moving around a lot, and some folks previously never interacted with others outside of their small village.

Nowadays they can still be found and utilised to get a grasp on what some people would call 'the basics' or 'common sense'. I have one laying around just to check whenever I'm not certain about something.