I've got thios idea into my head that there is a connection between
the IE "water" word *apa- and some of the various (but numerous) IE
pre/postpositions that contain a labial. Since I think they're part
of a loanword complex
http://www.angelfire.com/rant/tgpedersen/Op.html
it would be nice to find (loaned) cognates in the neighborhood.
Using the proposed historic developments given by Trask in "History
of Basque", I wondered if Basque <ibai> "river" and <behe>, <bei>,
<be>, <pe> "below" would been in Pre-Basque *iban and *beni (*bene?),
respectively (or *ipan, *peni?). Miguel?
If so, I would consider matching Basque <ipili>, <ipini> "be busy
with sth." with Latin <opulentia>, ON afl "harvest"
Torsten