Who is Hattie Johnson from The Illustrated Man and what is their importance?

Hattie Johnson is a black woman living on Mars. When she hears that a white man is coming by rocket, she is flooded with memories of hurt and pain. Hattie's husband stirs up a great mob against the white man, but she is unable to be sucked into their hatred. When the white man appears, Hattie takes the non-violent path of questioning, and he affords her the information that the world they remembered is gone. This knowledge allows Hattie to still the angry mob.