I don't think that the Latin limen is a good translation for the English threshold.

It's the only word I know for threshold in Latin. What would you suggest take its place? Or did you mean that limen is not an English word? My discussion of limen was merely a digression, and I always found it interesting that Latin had one word that covered two English words, i.e., threshold and lintel.

Ceci n'est pas un seing.