This is my all-time favorite Celtic harp-tale. I found it in the
Delaney (I think) collection. *The Harp of Fishbones* which Sylvia
carries, in a very slightly different form--the most noticeable
differences being that the "knee-woman" the one harper mentions is a
"wise woman" and his mother....and that the listening one asks instead
of says at the end, "Which makes you a harper?" --giving the answer,
IMO, more impact. Wonder if he used the source you cited.
Knee-woman...because she spent a lot of time kneeling to harvest
various plants, I wonder? My grandmother used to tell me that her
grandmother and mother were wise women, and I am sure that she would
have fitted that designation herself, with all the herblore she knew and
used--not to mention other things.
But that's another story....
--Barra