"For those who've been reading the press for the last two months, who question why we should even try, why we should accept the nullicy of cynicism, why we should listen to the voices of defeat, I'll tell you why."
And then he brought out a survivor of the 1984-85 Ethiopian famine - Birhan Woldu. Geldof said she was minutes from death as a three-year-old when she appeared in a famous video about the famine.
"Don't let them tell us this doesn't work," Geldof shouted.
Here are Birhan's words (translated):
"Hello from Africa! We Africans love you very much!
"It's a great honour to be here ... on the Live 8 stage. Please continue to support the Live 8, and we love you very much. Goodbye!"
Birhan is going to be an agriculturalist.