I have been given to understand that this refers to the probability that Foster came up with the melodies from listening to Black musicians -- ie, he lifted them.

I find the lyrics at best silly.

"the well of sorrow from which Negro music is drawn is also a well of mystery. I suspect that Stephen Foster owed something to this well, this mystery, this sorrow. 'My Old Kentucky Home' makes you think so, at any rate. Something there suggests close acquaintance with my people."