Ó Nolan wrote:
Aspiration of noun is often dynamic, i.e., employed
to mark certain psychological distinctions : ar bruach na farraige
—on the sea-shore (indefinite) : ar bhruach na farraige on a
(particular) shore of the sea.
What I find interesting is that this is essentially the opposite of the purported pattern in Scottish Gaelic --
air lenites only when it's describing an abstract state, not a literal location.
I'm sure my university lecturer gave a historical explanation for this, but he didn't include it in his notes (I'm looking at them now), so I can't really say what it was. But isn't it possible that the leniting form is the "memory" of a dative article, given that the second sentence is definite anyway, and the bruach would be lenited were it not for "na farraige" and the no-double-definite rule?
The difference between the Irish and Scottish Gaelic lenition patterns could then be explained by comparison of "I have a cold"
Tá slaghdán orm vs
Tha an cnatan orm.ScG is losing the definite article now, due to pressure from English -- as is Lowland Scots, incidentally. I caught
the cold many times when I was wee, but it's
a cold almost everywhere I hear now.
So it may be that ScG in the recent past saw abstracts as inherently definite, whereas contemporary Irish viewed them as inherently indefinite, and that the lenition patterns with
ar/air preserve the ghost of an article accordingly.