Lost bit of mindset?

Within Celtic reconstructionist tradition, there is discussion of achieving the appropriate mindset. A lot is made of gaining a certain familiarity with the language and culture. There are certain details that, no matter what we may try, we are most unlikely to regain. One of them struck me today.

All cultures have a concept of blasphemy or tabu. There are places you don't go. Actions you don't perform. Words you don't say. Even if they don't use those precise terms, there are danger zones into which a member of the group cannot move without suffering certain consequences. Not every member of the group may agree on them, but there are always limits. Modern paganism is not immune to this. Many treat Christianity as the tabu zone despite claiming respect for all faiths. Other terms mark the boundaries past which offense to the speaker's concept of orthodoxy or orthopraxy has occurred. Eclectic. Fluffy bunny. Folkish. It may not be called blasphemy, but "please don't do that where I can see it" is only a polite version of "get thee behind me."

I'm not saying those limits shouldn't exist. I firmly believe that limits are necessary in many areas. I've used all three of those terms to mark the place past which I will not go myself. What I'm coming to realize is that in all of the details we wish to reconstruct in Celtic paganism, one thing we lack and may never get back with any surety is what our ancestors felt to be blasphemous speech. We have a lot about what the Christian Celts thought qualified, but what came before is one of those areas of research I haven't seen touched on. I'd love to be wrong.

And I refuse to assume they had no such concept. I can't think of a single culture that lacks a forbidden zone. Even in modern American society, we see boundaries and discuss the concept of "dirty words." Certainly, it's easier to find entertainment that uses such things than it used to be (thank you, Lenny Bruce). But we all know we're working with material that polite society isn't supposed to be so free with. I myself was considering tidying up my speech when I realized I would be doing it to American standards instead of Celtic.

Am I blaspheming by muttering, "Mother of the gods" when I feel annoyed? Or am I entering the wrong territory for pagan Celts if I speak of bodily functions with four-letter words in the same context? Or is it both? I wish I knew. It would enhance my understanding of how they thought immensely.