The ranz des vaches is a type of mountain tune, played on the cor des Alpes (Alpine horn) and so charged with feeling for those bred to its cadences that under the old regime it had to be prohibited within the royal precincts because the Swiss guard would desert or commit suicide on hearing it.
That’s going into a story somewhere, somehow.
Unknowing 
Is this from Barzun’s book on Berlioz?
Yes. A surprising, wonderful work considering how dead—at least the last time I looked into it—his Dawn to Decadence turned out.