Postby thegooseking » March 8th, 2014 2:14 pm
くろくまさん、
I always assumed that the ~なさい in these words is the same as the imperative ~なさい. At least in お休みなさい you are telling someone to do something (specifically, to rest). It's a bit harder to see with お帰りなさい because you're telling someone to return when, in fact, they have already done so. ごめんなさい is the same, although めん is actually a noun, so the ~なさい takes the place of する. (It's actually more correct to say that めん is already a noun, since the other ones are technically being turned into nouns by using the ます-stem.)
Adding ~なさい to the ます-stem of a verb normally creates a quite abrupt command, but these statements are polite. I just put that down to the お~ or ご~ prefix at the beginning.
On a deeper level, as for the grammar that causes this, I'm not entirely sure. You're right that it comes from 為さる, which is a special class of Godan verb (I think the ending is actually -aru, not -ru), but beyond that I don't know, I'm afraid. However, I do think it's the same grammar that makes いらっしゃる become いらっしゃい. It seems like this is the ます-stem of -aru verbs - drop the る and add い.
All of these (お休みなさい, お帰りなさい, ごめんなさい and いらっしゃい) can be made extra-polite by adding ~ませ, which is the imperative form (though a different imperative form) of ~ます. However, this needs some care, since while it is polite and respectful, it is also quite impersonal, so it's really only something you'll hear hotel staff say to customers, and things like that. Using the impersonal imperative in less impersonal situations is, in contrast, quite rude.
小狼
