Piety might be a form of decorum, or a more serious way of understanding decorum. It is as much of a profanation to pray at a football game as it is to play a football game inside a church. Maybe that's what KB means by piety as a sense of "appropriateness."

I remember seeing the title of a Greenblatt book or essay, "Learning to Curse." It is a quotation from The Tempest, of course. But I was disappointed when I discovered it was not an autobiographical essay on how Stephen Greenblatt himself learned how to use "profane" language. That would have been much more interesting that what he came up with. The rules of cussing are very complex, and an introspective account of how someone acquired this system would be fascinating. No such luck.