Zuckerberg closed his speech with a Hebrew prayer, Mi Shebeirach, that he said he recites whenever he faces a challenge and sings to his daughter when tucking her into bed. Standing in front of Memorial Church, he told the story of an undocumented student from his Boys and Girls Club class who, despite every reason to be cynical about his own future, asked for a book on social justice as a birthday present because he wanted to help other struggling students. If a high school senior who doesn't know what the future holds can do his part, Zuckerberg said, then we owe it to the world to do ours.