His immediate muse was this guy...the Jewish Mark Twain!
http://en.wikipedia.org/wiki/Sholom_aleichem
Well the most immediate muse was still the Lord.
Harnick didn’t pick any old thing out of these works.
Some are of spiritually dubious origin yet, like the dream visions of the expired relatives, which in the production are hinted to be made up stories anyhow. But given a firm biblical context, evil is still constrained and God makes even human encounters with it be part of His work to the good. It is a beautiful story of the liberty of love and how it struggles with the framework of traditions. The larger point: Tradition isn’t there for its own sake.