In an older Greek dialect ‘sanity’ used to be called ‘brakes’; you know like the brakes of a car. One would say ‘are his brakes in a good state?’. There was no questioning about whether his engine was in a good state, it was just about brakes.
Children don’t brake that much, like you might have noticed. And as they grow older they hit on those brakes more, they become more ‘mature’. Well, they don’t do it all by themselves, of course. They do it with the help of their elders. And the more they hit on their own brakes, the more they hit on the brakes of others too –children included. And that becomes a circle –one stops the other. ‘This is bad’, ‘that is wrong’, ‘that’s ridiculous’, and so on. And you’re supposed to think about it twice before you make a deliberately silly remark on facebook, leave alone out on the streets. Your words might brakes somebody’s bones. And after all that stopping each other, a whip called ‘money’ is needed to force us get our engine work. It is the proper and mature thing to do.
If your family, or neighbors or colleagues don’t want to hear you sing, you just wont do it, and similarly if others don’t want you to be playful and happy, you will have to contain it.
The greatest crime in my classes was to talk with others and not pay attention, but what would really piss that teacher off was to laugh.