According to Walker, how has the creative spirit of black women expressed itself in the past?

This is a 1972 essay by Alice Walker. In it, she draws upon the writings of Jean Toomer who, in the post-Reconstruction South, witnessed a generation of black women who had seemingly gone mad, become "Saints" who sang "lullabies to ghosts" and went through their lives without fulfillment. Walker's interpretation is that this was not, as Toomer saw it, because they were unusually "vacant," having been beaten down by their difficult lives. On the contrary, she sees them as "Creators" and "Artists" whose spirituality was so deep and unwanted that they went insane because of an inability to express themselves. Unable to release their creativity, they went mad.
Walker poses the question to the reader: what happened to geniuses who were black women in the time of slavery? For a long time, as Walker points out, black people were forbidden to read or write and had no capacity to express themselves through physical artistry. Many, such as Bessie Smith, Billie Holiday, and Nina Simone, expressed themselves through singing, a later evidence, Walker says, of the gift which was stifled in black women of earlier generations. For many black women, singing in church was the only expression of their deep creativity permitted to them.