How has Harriett grown up? How is this revealed in what she says to Sandy and Annjee?

Harriett has made a career for herself, and she encourages Sandy to get his education. She reminds Annjee of Aunt Hager's great dreams for Sandy and that in a white man's world, black people cannot let brains go to waste. Sandy will have his education, she maintained; he is to make himself something and help the cause of black people everywhere.