Is autem an adversative or copulative particle?
Well, to my surprise, L&S says it's both, literally:
I. conj. [v. aut init.], on the other hand, but, yet, however, nevertheless; sometimes an emphasized and
Primarily, autem, it's adversative.
Update: to answer the question about which (copulative or adversative) is more frequent, I did the following:
- Searched autem in the Clementine Vulgate. Unfortunately in Perseus it is a stop word, so it is excluded from searches and won't yield any results.
- Chose two books: namely Genesis and the Gospel of St. John.
- Picked ten occurrences of autem from each book: the 1st, and then every tenth, i.e., the 11th, 21st, 31st,... until the 101st.
- Saw how were them translated in the New American Bible.
Methodological caveat: N=20 is too small a sample size, especially considering that I'm just using two books involving one (or a few) [human] writers each, and maybe two or three translators that lead to a unitary translation.
My results are:
- 6 occurrences of autem were simply lost in the translation
- 1 and (Gen 1,2, I recall this one being translated as but somewhere else)
- 1 yet
- 1 but
- 1 however (totaling 3 adversatives)
- 4 buts
- 2 lost
- 1 now
- 1 for
- 1 [while], with brackets (Io 7,12)
- 1 then
Of the last three, none is listed as a meaning by L&S, and only the while is arguably adversative (it is used in the sense of in turn.) Maybe it's just my idea that they were translated at all.
My opinion has gone from adversative is obviously more frequent, to look!, there is this very frequent, ambiguous meaning that may be easily seen as any, or both at the same time..., or none. Note that there is only 1/20 plain and. L&S put it like this:
it joins to a preceding thought a new one, either entirely antithetical or simply different
This usage is actually very common (almost as a pet word) to join two separate episodes in storytelling, and sometimes it's not even necessary in the translation.