Jonathan Miller posted two articles awhile back about spirituals . . . check them out here and here.
Here is a little from part one:
It seems to me that, for many of us, the spiritual has at its essence the quality of a gift. There is a sense that we have been given the spiritual through grace—through no merit of our own, simply by something outside of ourselves. A gift is not meant to be hoarded; it is meant to be shared, to be passed on to others. It did not come from us and does not accrue to our credit, and we must give it away if it is to have lasting value and power. The spiritual is part of our cultural heritage, and it powerfully enriches our lives—but none of us owns it.
And part two:
The central characteristic of the spiritual is “the moan”—that fundamental grounding in the sorrow of a people who were subjected to cruelty as a matter of course. Nevertheless, I always feel better after singing a spiritual. It doesn’t matter much what the text is. I would guess that spirituals affect others in similar ways. I even feel better after listening to spirituals, if I’m not singing. Other writers have praised the deep quality of spirituals wherein they affirm our common humanity; and once again there is that quality of “we,” that we are not alone, not even in our suffering.