Gates' purpose in telling the story about watching Nelson Mandela walk out of prison was to illustrate that there's hope for humanity.
Nelson Mandela was an activist. He fought for apartheid and discrimination against blacks in South Africa. He fought for the freedom of black people. This eventually led to his imprisonment.
Later he was eventually set free from prison. This represented hope to the people. It illustrated that we are all equal. This illustrated that there's hope for humanity.
